Please help

Every month a few days before my period starts I get this cut down near my vagina, (it’s not an std because I’ve been tested for them all) it’s like on the inside. It only sticks around for a few days then it’s gone till next month. Does anyone know what it is or have a remedy to help? It burns like a paper cut. I even had one when I was at my genyo and he wasn’t worried about it, could it be something with my hormones during that time?