Vulvar Rash That Hasn’t Gone Away In Months, Is It A STD Or Just a Rash?

October 28, 2018, I gave and received oral to a guy that I had been talking to for some time . Almost a month later, I had a terrible burning and itching rash. One above my vaginal opening which doesn’t hurt but is raised and another under my vaginal opening, which is red, lumpy, and is causing all of the pain. Sometimes my clitoris is itchy as well, and my anal region burns slightly but not as irritating or as much. My discharge looks normal and smells normal. I’m not experiencing any weird periods either. Also, in this same time period, I gave oral to another guy after me and the other guy stopped talking. He got tested a few weeks later, and everything came back negative. The guy before that I received oral from said that his ex also took a std test months before October and she was negative for everything as well. However, I’m not sure to trust that given that it’s possible he hasn’t gotten tested and I haven’t either. The rash gets worse with scented wash items and shampoo/conditioner. The rash above the vaginal opening has been going down, but the rash that’s causing the trouble is fickle; however it doesn’t burn as much as when I first discovered it, it is way more manageable. I do not think that I have an STD. If it’s just a rash like I’m thinking, then I’m wondering what to do to make it go away. I’ve changed my routine and I even tried some yeast infection treatments at some point.