Heavy bleeding 15 days after period

When I am not on the pill I have a frozen pretty irregular period, I usually go 28-40 days between periods. I stopped taking birth control in April.

This last cycle lasted around 53-54 days, the longest I can remember. I took multiple pregnancy tests over the course of two weeks, all negative. My period finally came July 11th. I have fairly light/medium periods.

This morning I woke up with very heavy bleeding and a lot of thick mucus. I have been bleeding heavily all day long. Nothing like this has happened to me before. I feel dizzy and have an awful headache as well. This can't be my period and I haven't had sex since I got my last period so this can't be a miscarriage. Any advice? I'm thinking of seeing a doctor if it doesn't stop.

Picture from when I first noticed it. The same amount of blood and mucus is appearing every time I wipe. WARNING: pic is TMI af