PLEASEEEEEE HELPP !!!

Okay so I just started taking birth control pill the beginning of June, I started birth control due to how bad cramps I had and how irregular my period was . But I started my period I want to say it was Tuesday or Monday but yesterday I had the worst cramps EVERRRRR !! And I’m guessing it’s because I’ve been getting a lot of blood clots coming out . And this recent blood clot I got it had white stuff in it, it looked like it was skin but had blood on it . I got scared so I asked my mom about it and she completely blowed me off and wasn’t no help and so looked it up and it said something about it was tissue so should I be worried or what ? I really need help I’m only 16 and i don’t know what to do