We have a 18 year old cat. He's been acting weird in the last few months, meowing like in pain before drinking or pooping. He's otherwise healthy so I wasn't really that worried about it, but in the last three days he's started having the weirdest behavior. He's humping the air like he's masturbating, with his thing out. Mind you, he has been neutered for 17 years. He does it frankly 5-6 times a day now, and it's pretty creepy. We're going to try to take him to the vet this week, but I can't even start to imagine how to describe that problem to a vet. Has anyone ever seen the same thing?