Hi im a 21 year old female, who in the past few years put on extra weight from a 5'5 150 to a 5'5 200. for the past few months ive been having a sharp pain in my left back side right below my rib cage. Just recently ive been feeling it towards the front left side of my stomach. and today when i went to the bathroom i had blood in my stool. I noticed that my stool was a dark brown with a red tint. This of course freaked me out. I dont know if anything about my weight or the pain in my side has anything to do with it?help!