Rashing and itching

I have developed a type of rash on my vagina that stings and almost feels like it’s covered in paper cuts. It’s red and looks a little rashy. This has started to spread over my body as well. I have already gotten STD tested and everything is negative. The rash around my vagina gets worse when I wear pads or liners so I believe I developed an allergy and it’s not quite going away because I use pads frequently due to my cycle being shorter than most. What do you guys think? I’m going to get it checked out but so far I haven’t got any answers.