I have a rash on my vagina, help?

Ok I'm embarassed to ask.I'm guessing its not an std because I'm a virgin and haven't done anything to change that.The rash isn't blistering, butits around the area where the end ofyour underwear is between the leg and vagina. I don't shave down there and the rash is also around my butt. Please give honest answers I'm 14 and a little terrified, I don't wanna tell my mom because then she'll think I caught an std. Please help it took me a lot to finally be able to ask