Hi
Welcome to the MedHelp forum!
There is a chance that you have compression of the spinal nerves in the lumbo-sacral spine region. This can happen due to overuse of the lower back as in work requiring too much of bending, lifting weight, fall on the back, overweight, canal stenosis, bone disease, spondylosis, poor posture etc. Poor posture while sleeping, sitting on computers or jobs for a long time, uneven bed, exposure of back to cold air while sleeping can cause a discomfort for a few days. Take a multivitamin, plenty of fluids, and an OTC analgesic. Apply a local analgesic and apply a heating pad and see if it helps. If this does not help, consult a neurologist. A MRI of the spine will be definitely required and nerve conduction studies may also be needed. The treatment is to remove the compression. You have to discuss the best treatment option with a neurologist, which can range from medication to physiotherapy to traction, lumbar belts, lumbar corsets or even surgery.
Other than this it can also be due to pelvic inflammatory disease. You will need to consult a gynecologist regarding this. Take care!
It sounds like what my husband had. He thought that it came from an old lifting injury. but when, he saw a chiro, the chiro said that it came from two things (posture/that one of his legs was slightly shorter than the other). You can't tell by looking at him that one of his legs are shorter than the other, but the chiropractor said that was the case. A doctor will know for sure. You should see a chiropractor or an orthopedic doctor.