I almost guarantee I have social anxiety or avoidant personality disorder. It was "diagnosed" by some test I took that the high school psychologist had me take so I don't know if it's legit but I am certainly not normal.
Every interaction I have with people is uncomfortable, I have extreme anxiety before any social thing, be it "big" like a presentation or job interview or small like having to walk back to my dorm room with someone other than my three friends (I've had to walk with my friends boyfriend or one of my roomates who is not my friends and it's extremely nerve wracking even though I'm quite comfortable with them if there are any other people also involved, being one on one is BAD). I am either a nervous wreck or completely numb during the interaction, I am generally very nervous during the smaller things, constantly thinking about how awkward it is and what they must be thinking about me, etc. but can go mentally numb (that's what I call it) during presentations/interviews so long as nothing goes wrong. But I will still physically react with shaking, sweating, shaky voice, pounding heart, etc. Also being mentally numb isn't good if the teacher/interviewer is going to ask something I didn't prepare for (even if I know the subject inside and out). I can't think at all so if I didn't memorize a response I can't actually think enough to produce a decent answer. I frequently cry if I think back on social interactions I've had, lately I've been crying myself to sleep a lot because I lie in bed and think about interactions I've had with my friends/family and how they failed or how they prove those people don't really like me. I can take the smallest comment someone made and turn it into proof that they really dislike me.
The biggest issue I have with my problem is just that I work myself up so badly that I can't go through with things. I get myself into such a panic before everything. Every time before going to babysit I'd be a mess even though every single time it went just fine. I worked myself up for weeks to finally go to the gym downstairs because I was afraid I'd look stupid/fat/out of shape to people who saw me there or my roommates. I almost didn't go to class the other day because in the previous class I hadn't finished as much work as most of the class and was afraid he wasn't going to give any extra time for us to finish up and would have a half finished white board to present. I skipped class because I didn't do the homework and was afraid I'd be called on for it. I won't go for extra help in a class and even if i could bring myself to go I highly doubt I'd absorb anything they say because I'd be in a panic the entire time. I also cannot do work while being watched, it's like my brain suddenly shuts off and I can't add and subtract or make simple sentences anymore. I can't call people, even my friends. I won't call my siblings on their birthdays. I got my brother's girlfriend very upset because I didn't answer a facebook message asking if we could get together soon. I didn't want to because I'd be an anxious mess the whole time but saying no is just mean, so I ignored her and now, according to my mother, she's mad and I feel horrible. And I can't explain it to ANYONE because if I try I immediately start sobbing (like right now). That's one of the main reasons I don't want to go to a therapist. When i'd see the one at school I'd either try to talk to her about myself and cry or just lie/avoid answering in full to avoid crying but still satisfy her question. I left every single session miserable, plus my eyes were puffy which made me super self conscious. My English teacher probably thought I was in a deep depression.
So yeah, I'd say it impacts my day to day life and will possibly impact my future when it comes to graduate school or a job. I still sometimes think it's just personal weakness, that I should be able to do these things, like get extra help in school despite the anxiety, or that if I force myself to do things that it'll get better. But you know I've had to talk to people my entire life and I still fail at that so...Maybe I should get on meds, I just don't see how they would work when it's my own thoughts that cause a lot of the issues. Meds can't change my thoughts.
It's also possible I have something else to go along with social anxiety. I don't desire a romantic/sexual relationship at all, I never want to have sex, and dislike touch (find it extremely uncomfortable in most cases), and have an oddly strict moral code when it comes to drinking/drugs/sex (like I become absolutely enraged on the inside when my friends talk about drinking (not drunk driving or doing anything dangerous, but just getting drunk and acting like idiots). It's like they're talking about participating in dog fighting, that's how angry I feel. Even though logically I know they aren't doing anything bad and I'm the one whose odd, I can't help feeling very angry about it, though I keep my mouth shut because I know I'm wrong). Those things don't really fall into SA, but of course it could just be my individual personality.
That said I don't have panic attacks (at least I don't think I do lol) and people who don't know me/aren't around me a lot don't always know I have a problem, particularly if they only see me in formal social situations, where everyone is nervous. They just figure I'm shy but am normal in "my element" or with my friends. But I'm not, once you see my freaking out about going to the gym you start to realize I have a problem. Though I generally hide any freak outs and do any crying in my bedroom.
A doctor (not a gastroenterologist nor a psychologist) once told me my stomach problems are "an anxiety disorder." I disagree with that one.
Not saying it is the case for you, but my brother had some horrible stomach problems, pain diarrhea, etc. It caused him to miss many days of school because he's get it the worst in the mornings. He started with a gastroenterologist who started testing him for a bunch of stuff, he swallowed a little camera and everything. They couldn't find anything but started him on some sort of stomach med anyways. Didn't help much. Then he started going to a psychologist for some general anxiety issues about school and some depression, he got on anti-anxiety/depression meds and the stomach issues disappeared. For him digestive upset was his body's reaction to anxiety. So it is possible.