Given the symptoms that you report - pain in the lower back, hips and leg provoked by lifting heavy weight - the symptoms are probably due to pressure on the roots of the sciatic nerve as they are coming out from the spine. Pressure like this is usually due to some type of disorder of the lumbar-sacral region of the spine or the surrounding tissues such as the muscles and their tendons. Such disorders can be caused by degenerative changes of the spine (spondylosis), trauma, static disorders of the spine, or combinations among them.

Besides a physical examination, you can request an MRI of the spine to identify the reason for the nerve damage. Therapy will depend upon the cause of the pain and the level of nerve damage. Painkillers are used for temporary pain relief. Physical therapy and surgery are used to relieve the nerve from the surrounding pressure. You can consult some orthopaedist about your condition for a diagnosis and follow up.