I have had gastro and stomach cramps with lower back pain for three weeks if i drink gastron it stops gastro but i get bloated and diarrhea is back in a day. anything i eat cause diarrhea have little to no appetite and drink water, but feel tired?

Diarrhea : There is a large list of possible reasons for these symptoms. A viral condition is high on the list. It is difficult to address your question with more information and a physical examination . Keep isolated it can be COVID 19 and see a doctor via telemedicine

Prolonged symptoms: After three weeks of diarrhea it's time for stool culture to check for bacterial pathogens or parasitic intestinal tract infections. Gastron is not recommended for infective diarrheal conditions. Drink plenty of room temperature fluids, flat ginger ale helps nausea. Diet should be bland,nonoily, with no harsh roughage. Rather than drugs like gascon I recommend kaopectate&See gastroenterologist.