Hi, In Between My Anus And Vagina That Are Red,

Hi, in between my anus and vagina that are red, scabby, and burn/itch. I noticed these 2 days ago after wearing an uncomfortable thong and they are still there. I thought that this could be from my thong rubbing against my skin, but I am not for sure. I have been tested for STDs and was STD free. I have not been sexually active since