hello. Last thursday i got a adorable mini Australian Shepherd (almost 3 months old)and named her Layla. She's a very active and sweet dog. Instinctually, she tries to herd me in the backyard by nipping at my feet and laying down to wait for me to move so she can nip me again. However, sometimes when she doesn't want me to do something or she wants me to put her down she'll snap at my arm or hand. I was told that when a puppy is playing too rough that you can hold her down on her back and until she stops squirming and tell her no. Supposedly it represents something similar to what her mother would do, but when i do it she yelps as if i'm hurting her and when i let her up she backs away from me like she's scared. I definitely don't want her to be scared of me. She hasn't even been in my house a week and doesn't understand "No" or anything else for that matter. Help?