IBS and IBD are two distinct diseases and they are both different from Gastritis. Please get a second opinion from a different doctor. If there are internal wounds in your bowels, your doctor will do an Endoscopy and determine what's wrong. Don't wait for it to get better on its own. the sooner treated, the better. Ayurveda also has good treatments for this disease. You can get free ayurvedic treatments from Borella ayurveda hospital. Yoghurts aren't probably good as acids are added to them. For the time being avoid red meats such as beef, sodas, alcohol, kottu, fried rice. basically fried and acidic foods.