[TMI] Please help

So, for the past 1.5 hours my period blood has been very runny, I go through a tampon in 20-30 minutes. It's never this heavy. I was sitting and felt like it was running through, it WAS. I pulled my tampon out, and then a BIG clot followed behind it. Nothing like this has happened. Is this normal? It's scaring me. The one not on the tampon is the one I picked up. It's huge and think and so is the other.