What Causes Vaginal Pain And Burning Urination?

I started a new sexual relationship about 2 months ago. Last week I began having burning during urination with what I thought was cloudy urine. Now my vagina feels raw and I now have urgency. I took trimetheprim sulfa but Im not sure if I may have an STD vs. UTI. I realize testing is the only way to be sure. Any other suggestions?