Have bright red blood in stool, including a lg clot. now feel nauseated, light headed, and dull pain mid back left side. should i worry?

Go to the ER: Bright red blood in the stool can be from several benign causes, such as blood vessel abnormality, diverticulosis, a polyp or hemorrhoids, or from more serious reasons, such as a colorectal malignancy. But if you passed a large volume enough to make you light headed, please go to the er to be checked out, including blood work and observation. You may need to be admitted and have a GI doc see you.

Blood in stool: Blood in stool is always an issue of concern it may be that you have a hemorrhoid, but see your doctor for evaluation. He may want to refer you to a gastroenerologist for further evaluation.

Yes: I could be a variety of things including ischemic colitis , hemorrhoids contact your primary care.