What Causes Chronic Diarrhea And Gastritis Despite Taking Rablet D And Providac?

Hi, few weeks ago i have an episode of 2 weeks long direah and doctor found small ulcers in rectum transverse and sigmoid colon. After hospitalization for 4 days i have recovered and start taking rablet d, equirex and providac. After 15 days of normal stool and digestion sudden ly last week i started feeling gas in my abdomen and since thursday i have watery stool thrice day. Doctor gave me colospa retard and enzar forte but still todday i have watery stool and gas. What more to be done?