Hello SWG - I did a few things and it kind of solved the problem. I took antibiotics (Ciprofloxacin 550 twice a day) for about 10 days. (earlier I was doing shorter course). I stopped drinking tap water, I use a purifier at home & bottled water when outside. I try to eat freshly cooked food and stopped eating leftovers most of the time.
After doing all of this, my diarrhea episodes have been reduced greatly. My doc thinks it all happens due to bacterial infection and because of low immunity.
Hope this info helps.