What Is Causing Burning Sensation In My Clitoris Area While Driving?

I have been having a burning sensation near the clotoris area. I am not sure if it is the clotoris or the urethra. I am a bit overweight so can see if there was s any swelling or redness. It burns when I urinate. Some days worse then other days. I have been on two sets of antibiotics amoxil and cipro but with now relief. My urine tests also came back negative for utis. It seems so get worse when I am sitting for long times or walking and driving alot. Heat seems to help a bit for the burning sensation. This has been going on for 3 months now. It has been the worst time of my life. I cant go anywhere not even to a shop. My husband need to do all the shopping. I cant take my kids away from the house because I spend all my time in a hot bath or with a hot water bottle to try and relief some of the pain. I really dont know how long I can keep this up anymore...