Black discharge

ok. so. i was 10 days late. my boy friend and i did the long distance thing. he came into town, he had sex a few times. i am not on birth control. the first two times we didn't use a condom. we were practicing that old pull out method. on the 3rd or 4th day we were using a condom but he thought a little but of his cum got in side of me. so the next day we went to planned parenthood and took the pill.
eleven days later i started spotting. and then bleeding enough to fill up a tampon. but its dark. and that was it. no more bleeding. the next day dark sticky tar looking stuff was showing up. what the heck is it?? everyone says, it's not possible to have your period and be pregnant, but then there are people who say some women get their period during the first trimester. who knows. i am stressed cause the dang guy dumped me at the airport. classy. and my ulcer is flaring up, but the pain is in my entire belly. not just where the ulcer is. i burp a ton. even when i don't eat anything to upset my ulcer. its a warm feeling all over my belly. i know i should just pee on a stick. but really, i mean i bled. what is this black crap coming out of my vagina!!