weird period... anyone else?

so before i start this, usually my periods last 5 days and lighten up to only a little bit of blood to almost none on the 4th day. i have never had an extremely heavy period. i could use 2 tampons in one day and be fine. i just started what i thought was my period on august 21 and it has been extremely heavy. i have went through 4 almost 5 tampons a day completely full that i started leaking about 4 hours after putting it in. three days into this “period” i pulled out my tampon and a huge blood clot fell out. again, i have never had a blood clot either. this is very different and odd for me and i am sexually active so i was asking for advice. does anyone think this could be a miscarriage or just a heavy period? i’m going to the doctor tmr.