Could this have been a miscarriage(this is kinda gross guys.. read at your own will.. lol)?

i got on the depo shot in october, but the doctor didn't give me a pregnancy test before he put me on it. i've been on it before, but never had any real side effects, besides my period came only once every 3 months rather than once per month. i had been off of the shot for about 2 years before i started again in oct 09. two weeks after i got on it, i had a very heavy, disgusting, and painful period that lasted nearly 3 weeks. sometime in that 3 weeks, there was a very nasty gray-ish colored discharge that came.. actually, i wouldn't even call it discharge, it was a more solid than discharge, and pretty large.. not the amount of typical discharge- and was very waxy and gummy feeling. i didn't think anything of it, i had just heard that the shot affects different women in different ways. because of this though, i did not renew it in january like i should have. recently, a girl i work with had a miscarriage, and it's been something widely and openly talked about quite a but at work.. now i'm starting to wonder if what happened to me could have been a miscarriage? or just side effects of the shot? is it possible that i was already pregnant, and then a combination of the shot, plus the fact that i take prescribed adderall 3 times a day, could have been enough to cause me to miscarry? i guess my biggest concern is the gray colored gummy-feeling glob that came out of me.. what could that have been? is this worth calling my doctor for?