Had my period for 12 days straight it won’t stop !!

I started my period 5 days early on the 19th of February the first 3 days it was light spotting then it got heavy the last 4 days and now it been light I see little clumps go in the toilet and only see it when I have discharge or whip myself I don’t know what’s going on I haven’t had this before I went to planned parenthood 2 days ago they said i wasn’t pregnant and it was nothing wrong with me I’m scared in don’t know what else to think or do