26 y.o. woman, the condom broke without us noticing. I took the morning after pill just in case.

I've always had strongish vaginal discharge but a few weeks later, I got odoreless, dark brown discharge and slight vaginal itching. Now I'm wondering:

- could it be from the morning after pill messing with my hormones?

- could it be an STI?

- could it be from ulceration of the uterus? (my gyno is supervising it)

It's early for my period, so it's not pre-menstrual discharge. What do you think it's the cause?