Hi
Thanks for writing to the 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. A MRI of the spine may be required. Do discuss this with your doctor and get yourself examined.
Hope this helps. Please let me know if there is any thing else and do keep me posted. Take care!