scared.. PLEASE HELP... if you can

ok... so about three days now I've been having severe cramps and dizziness and nausea. this week is supposed to be my period week. currently on day three but the bleeding has not gotten heavy. it was Brown then pink... then it stopped... few hours later it's a little brown again. only see blood when I wipe and a little on my pad. not enough to full and I should be having quite a period by now. before all this, during my ovulation week I took a morning after pill two days after my bf came inside me. now I'm totally confused. took a test last week Wednesday cause I had it laying around and it was negative. I have no idea what is happening inside me. please help