Please help me! I caught my garter snake as a baby in 2011 and feed her small feeder fish and she has grown to be around one and a half feet long. I bought her ten feeder fish yesterday and she usually eats them immediately and finishes within an hour but hours passed and she hadn't eaten any. I picked her up and she felt very light and frail. When I reach ino her habitat to hold her, she usually slither away from my hand but she didn't try to get away and even when I held her she wasn't moving much. I looked at her scales on her belly and it looks like some parts have just been plucked off and she has 2 or 3 bald spots... they aren't bright red and don't look irritated... I just know that's not normal. Today I got home and she had eaten 5 of her 10 fish. I watched her for a little and she kept opening her mouth and her body kept rippling from her tail end to the direction of her head, like she was trying to throw up and push up the fish she ate. I reached my hand in again to see if she would shy from it, but she still didn't.
Her habitat consists of wood shavings, hiding spaces, a water bowl, a heated side and a non heated side. She isnt favoring either side off the terrarium over the other and she had been shedding regularly. A few days ago, I had left on a trip for 4 days and I came home and her water bowl was empty, but I had filled it before I left. She usually takes about 3 days before she finishes her water but of course there is no way for me to know if she finishes it sooner or not and maybe went more than a day without water.
I see no difference in her coloration. Her eyes aren't cloudy. I'm wondering if it is a digestion problem in itself or maybe she got dehydrated and hasn't recovered or maybe has a worse disease like mites. My garter snake is the only snake I've ever had and I've not taken many precautions to prevent whatever diseases she may naturally be vulnerable to.
What could be wrong with her and is there anything I can do?