5 weeks, burning sensation?

I need help! I am 5 weeks 4 days pregnant, I am experiencing a burning sensation down there, not when urinating but inbetween, if that makes sense. I went to the doctor last Tuesday and I have no infections according to my urine test. It's very off and on and doesn't happen everyday. Has this happened to anyone else? Could it possibly just be an increase in hormones going on? Any input would be appreciated! :)