So this morning I went to pick Philly up out of her cage for lap time and she started squealing like she was afraid or something but was fine when I cuddled her. I could pet her back no problem and she would even close her eyes. I started messing with underside a bit and she would lunge at me like she wanted to bite me and would squeal. I could lightly squeeze her sides no problem but it seems to be her underside. I manage to look at her stomach but it looked normal. She is about 3 months old and eating and drinking normal. She is also pooping. I don't feed veggies that are too gassy no cucumber or broccoli. I'm not sure about mites as I though they were all over the body. She also gained 2 oz in a week so she is 1lb 10oz as of yesterday. What could it be?