I had diahrea, nausea & vomiting daily for 2 weeks. after the 2 weeks i was sent to the er with extremely severe chest and back pain. the doctor didn't know what was wrong. i found out later from research it was dehydration. why would my chest hurt?

Gastritis?: If you had persistent nausea & vomiting without cough/breathing problems it is very possible you had significant inflammation in the stomach & /or esophagus, which could cause pain felt in the chest & possibly the back. I assume you had some testing done in ER to rule out other things. Pepcid famotidine) or Prilosec (omeprazole) can help these symptoms, as well as avoiding alcohol & antiinflamma