I am 44 and been on the depo prev ea for many of years. since sept 2013 i have been spotting on and off. now i just had my shot and still spotting! ?

Thin lining: You could have a very thin lining (endometrium) due to the long use of a progesterone-dominant contraceptive. Break through bleeding can occur in that situation. Definitely check a pregnancy test to rule that out. A sonogram could tell you if the lining is thin. A polyp can cause irregular bleeding but you would need testing (sonohysterogram) to diagnose that. You may need estrogen add back.