Hello, I am 26 years old male.
I have long term diarrhea and it doesn’t stop for months.
So I consulted at a local hospital taking blood test and supersonic body check, and also had an endoscope.
The result was fine – blood test was fine, liver wasn’t bad, but had a bit of atrophic gastritis – not serious I was said.
And they asked me to take tetracycline and loperamid(if tetra doesn’t work). So took tetra 3 days and loperamid 1 day. At first it looked like it’s working but after couple of weeks, I was having diarrhea again. I took tetra and loperamid, but it temporarily fix the problem and it comes again.
I am living with other friends and they are fine, so guess it’s not the food. And yes, when I drink beer even a cup, it gets very serious.

What kind of treatment should I do and what kind of additional check should I take?