PLEASE HELP

I recently got tested for all the stds. And all came back negative. I recently have been experiencing itching on my vagina. I have no sort of discharge at all. I have started myself on bactrim.. thinking it could be an uti. But now ive been on the antibiotic for 5 days and the itching hasnt stop. What could this be?? Like i said theres no discharge and theres no odor as well. Please help me.