3rd period this month...

Just need some ideas. This is my THIRD PERIOD this month I’m usually so regular that this is crazy to me. This third period is Soo uncomfortable and very heavy compared to the first two that were usual with my regular flow. What the heck is going on with me. I don’t have a doctors appointment till next Thursday 🙄.. have an odd feeling I’m having a miscarriage... my doctor can’t give me any information till my appointment no help at all.