Stomach issues?

So lately I’ve been having stomach issues, my abdominal area painfully burns when I haven’t eaten recently and every time I eat I feel sick (not nauseas but very uncomfortable) and usually I get extremely painful gas and loose stool, taking alka seltzer clears it up but I can’t take that every time I eat, it’s been 4 days now and I wouldn’t be able to get into my pcp until at least Monday. I know I probably need an endoscopy/colonoscopy, but idk if I can bare with it another 3 days, I don’t want to go to the ER because it’s not unbearable pain and no sign of internal bleeding,

I may have gluten issues but haven’t been fully tested yet, but honestly it doesn’t matter what I eat, I react badly