What Causes Bloating,constipation And Weight Gain?

Hi! Lately I always feel bloated, very tired in the evenings, have bowel movements every 3-4 days. At times get really bad stomach pains which sometimes results in diarrhea. Went to the ER one night because of the pain. And I ve gained almost 30 pounds in the last 3 months. My diet isn t great but I don t eat that bad to gain that much in that short time frame.