Abdomen bloating and discomfort. I take?

Hi, I am not pregnant.I have severe abdomen bloating and discomfort for past 5 days. I ate few meals from restaurant last week.i have also been taking NSAIDs (diclofenac sodium and ibprufen) last few weeks.i have upper abdominal bloating and discomfort, it's mostly on the right side. I feel nauseated and don't eat anything much. Also have heartburn and some bitter taste in the mouth. Even if I drink a cup of water, I feel nauseated and feels like vomiting. I took gelusil tablet for 2 days. I keep burping even if I don't eat anything. What else to do to make feel better? The bloating is still the same for past 5 days. I am eating only bread and banana. Still the bloating doesn't reduce. Does it require further diagnosis or what medicine should I take? Bitter taste in the mouth is throughout the day even if I eat food or not.