Hi doctor! I have congestive gastritis, after taking the medicine for a week, I feel better. The doctor asked me how should I eat with congestive gastritis?

Hi doctor! I had gastritis with an endoscopy in April at the hospital, and on October 17, 2020, I went to the endoscopy at a provincial hospital and still diagnosed gastritis, the chlorine test for HP bacteria was negative. Doctor let me ask, how long does it take to cure gastritis? Thank you doctor!