Abdomen bloating, heartburn, nausea.

Hi, I am not pregnant. I am having severe abdominal bloating.It's been there for last 4 days. And diarrhea yesterday.No abdomen pain though. The feel of heaviness is making my stomach so upset and I don't feel like eating.I didn't eat much in the last 2 days. Just eating some toast and bananas.The heaviness is more on the upper side(right) of the stomach and my belly looks so bigger than usual.I am belching more. I did take some gelusil and it gives relief for sometime. I ate some restaurant food in the last week for 2 days. I don't know if that upsets my stomach. Also, I was taking some NSAIDs (diclofenac and ibprufen) in the last few weeks. Taken diclofenac for a week and I got stomach pain. So the doctor told me to stop taking it. I was having fever and sore throat last week. So I have taken ibprufen for 2 days. After that, this bloating and heaviness started.It's so hard feeling in the upper abdomen.I feel nauseated.No vomiting. is it gastritis?what to do next to feel better soon.