Hospital Bills and Appeals

I went to the ER for a stomach ache. It was painful, but I ended up feeling better after fasting for a day and taking pepto.

The hospital is now billing me for having a life threatening condition?? I'm confused. They told me they're not certain but I could have an ulcer. They prescribed me a medicine for GERD that I didn't even end up picking up because it resolved on its own and never happened again.

I paid for all my labs and diagnostic imaging paid for the ER visit and pain medicine I received while there. Months later I receive this bill. Seems like bull. I want to appeal. Anyone have experience with this?