I Have An Undiagnosed Pain In The Left Lower Crease

I have an undiagnosed pain in the left lower crease of my leg/hip. I excercised each day of my last pregnancy, staying in good shape is hard for me, so I like to stay that way. I am a 42 year old female with 5 children, my last child was born 6 years ago. I had my first C-section with this last baby. Once home from the surgery my back did a strange popping and cracking about 6 vertebrae in my lower back, it didn't hurt . I went to therapy. My back popping stopped but a very serious burning developed in my lower left hip just inside my leg crease. The burning of the pain can spread to a dollar coin size, elongate to a dollar bill that follows the leg crease. It is lessened when I wear a very tight girdle around my hips. Sometimes it can become so terrible, it is hard to walk because of the referred pain to my back, down the inside of my leg, my hip can hurt to. Heat doesn't seem to help. It seems to almost make it worse? Sometimes I can get it to almost go away, all but the little burning in the front by my leg crease, on it near it, or in a line paralleling my leg crease to the inside.