Vulva problems :(

Hey y'all. I'm 22 and having some vulva and vaginal problems. Since December I've had issues with this horrible burning sensation around my vulva and vagina that just won't go away. I've tried everything from cortisone cream to vagisil. I've taken so many UTI tests that have all come up negative. I've gone to the DR multiple times. What do I do? I also need to pee all the time and its killing me. Some days are better than others. :( I cant use tampons or pads anymore.