What Causes Pain In The Buttocks?

I ve been suffering pain in butt with hot sensation for 15 years! My left hip also snaps like 30 -50 times a day and is made worse by periods! I ve had Mri s, X-rays, and it shows nothing and these damn doctors haven t a clue! I don t know how much longer I can go on like this! I can sit anymore and don t sleep anymore hardly because I can t lay on my hip or butt! Any ideas of what it might be, what doctors I should go to ect! I ve been to sports ortho surgeon and I m seeing a rheumatologist next! I just don t believe X-rays and Mri s show all problems so why rely on them instead of patients complaint! Also my feet get so cold when the pain in my butt is bad, hot sensation in butt and deep in the tailbone hurts with hip pain and even my pubic bone pops, please help I need to go back to work before me and my daughter are homeless, I ve been searching for answers for 10 years!