Hi Jojo,
Welcome to the Pain Mangement Forum. I am glad that you found us but sorry to hear about your pain.
The type of pain you describe sounds like sciatica. Sciatica refers pain caused by an inflamed or impinged sciatic nerve. The nerve originates in the spine and travels down the back of our legs. Anything that irritates this nerve can cause pain. It may be from a spinal structural problem but there are also several other conditions that can cause this pain. I suggest that you request an MRI. That at least would be a place to begin.
I have SIJ (sacroiliac joint) Dysfunction. The SIJ is located in your gluteal area and I have severe and intense sciatica. Sitting is the very worse position for me and will elicit extreme often burning, throbbing pain. Physicians looked for a spinal issue and when they could not find it they decided my pain was originating in my head. So I know your frustration in seeking a diagnosis. But keep looking, don't give up.
It sounds strange to me that Fibromyalgia would be localized. I have Myofascial Pain Syndrome in my right leg, it is sometimes confused with Fibro.
I encourage you to consult with another physician if the one(s) you are seeing cannot determine a diagnosis. Life is too short to live with uncontrolled pain. Please look in touch and let us know how you are doing.
Best of Luck to You,
Tuck
When we have a disc problem we can get pain that runs down the length of our legs even in to the feet. It also could be that. I have fibromyalgia and it would be odd that you have pain only in that area. Does stretching it out help? you said walking does help. I wonder if it's a touch of arthritis in the hip. If you are in a cold weather area it could be activated by that. If it persists more than 2 weeks get it checked out. Good luck.