Bleeding for a month

Last month, I started bleeding a week before my period. My bf and I were having sex, and that is what made it start. It worried me because it wasn’t time for my period.

I am on birth control pills and have been on the same one for 5 years and I never get breakthrough bleeding.

I haven’t stopped bleeding for 4 weeks now. Some days it’s light and some days it’s a little heavy.

I have a dr appt in a couple weeks.

Does anyone know what this could be ? Is it just breakthrough bleeding ??