What could cause me to taste blood when I burp? I ve noticed it only happens when I m menstruating. I ve asked my doctor in the past about the possibility that I have endometriosis but they dismissed it. I m not entirely convinced I don t have it, though. My cramps are severe and are present in my back and my legs down to my knees. The pain is only present the day I start bleeding. After that it subsides to mere discomfort. My flow is only heavy on the second and third day. On those days I typically go through 4-6 super-absorbancy tampons each day. Is it possible that it is, in fact, endometriosis and that s what s causing the bloody taste in my mouth?