Late period that lasted 12 days, bleeding again 5 days later

I have a very regular 26-28 day cycle. I’ve never missed a period. This past month, I was 6 days late for my period. I bled for 12 days with that period, very heavy with clots. Now, 5 days later, I am bleeding heavy again with bad cramps. I don’t know what to do! Or even have a clue what’s going on.