I Took A Plan B Pill 10 Days Ago After

I took a plan b pill 10 days ago after unprotected sex as a precautuoned, he did not ejaculate. The next day I was itchy and irritated at the vaginal opening and I side labia. Yesterday I started a heavy period with heavy uterine wall (skin like tissue) lining being expelled today. And as of yesterday I am extremely itchy and irritated. No burning, no sores. Last night i used one day YI treatmemt. No relief yet.
I intend to seek an std panel to rule out. However, unail then I'd like to know if plan b possibly caused the itchy irritation. And should I stick it out until the hormone is out of my system ??? Or is it ? Should I try a monostat 3 day ? So unsure of the itchy inflammation (not raw or burning ) . Help