Suggest Medication For Heavy Bleeding,back Pain And Cramps

I was 4 days late on my period. And i had a brown mark, then when i wiped was very light pink. I ut a tampon n in thiinking it was my period. And it stoppped and a couple hrs later it started bleeding again a little heavier but nothing at all like my period.i have really bad back pain and cramps. And this morning it was a stringy clear disharcharge with some blood in it.? Idk what this is. But there is a chance i could be pregnant.