Suggest Treatment For Severe Pain In The Left Side Of The Body

I started to have pain on my left side one night then the next night it was on my right it hurt a lot when I was in a car and laying down but then the next day it was on both sides I had a fever I went to the hospital thinking it was a uti but they said no it's flank pain now it's mainly on my right and I have hot flashes and fever and nausea what could it be