How do i confirm that i have a chest pain and aside from that i dont have any other pain, only bitterness in my mouth. and what should i do if the pain does not cure after i ate a painkiller?

Avoid use of painkillers unless recommended by your physician. Chest pain may be due to musculoskeletal inflammation or a pleural infection/inflammation. The presence of the other symptoms is most likely related to GERD, and esophageal inflammation may similarly cause chest pain. Musculoskeletal pain usually improves though with Ibuprofen. Consider GERD treatment after discussion with your M.D.