Hi there, I had really painful area extending diagonally across my thigh. I thought it might be a blood clot. It wasn't, but dr suspected pinched nerve. Had an MRI and the only pinched nerve was on the other side! I saw a neurologist. It turned out to be shingles without a rash.
I don't think you need worry about a specialist yet, but see a GP straight away. He/she should decide whether it's an emergency for a start. More likely will send you for tests then IDE who you should see. Good luck.
I would advise consulting an orthopedic doctor to diagnose the condition. Possibilities may include lumbar radiculopathy, sciatica, and other related conditions. In the meantime, try moist heat on the affected parts and some pain relievers. Avoid any movements that will aggravate the pain, and observe proper body mechanics.
I hope this helps! Take care!