I'm going from the bottom up, okay? :)
Your stomach probably IS just trying to digest! It was basically empty when you ate, and now it's trying to digest protein, dairy, and a little bit of grease. (That's good - you need to feed your body.) However, you're probably going to be pretty aware of the digestion process. It wouldn't be anything normal for you to have some gas, some rumbling, maybe even a little pain. It's just your body doing its job.
As far as the Pedialyte - maybe they just haven't restocked lately. Maybe the shipment was late. Maybe there's a bodybuilding show in town and a bunch of dehydrated athletes bought it up. You just never know. :)
I'm sorry you're not feeling well, but that doesn't mean it is going to be a sickness that will cause the symptoms you fear so much. After getting yourself well fed, you may feel better by morning!
I hope the meditation does help you. Stick with it and keep practicing. I really do believe meditation can be a very healing thing.
As far as groceries - this is the opposite of what my counselor would say. She'd tell me to go to the store more often to face my fears. (She's been making me drive scary places. lol) BUT - you're already avoiding stores, it sounds like. What size of city are you in? I've heard of shopping for groceries online and having them delivered in metropolitan areas. My husband won't go to the grocery store often (like, 4 times a year), so we sometimes order things from Amazon that most people would get during errands - soap, etc. - that he'd like to select himself.