Hi
Having had a prolapsed L5 disc in 1999 i have also suffered back pain (didn't know if I'd walk agaian)
With Sciatica it may not be that at all!
It will more than likely be your Piriformis muscle in your bum cheeks:
The Piriformis muscle is one of the small muscles deep in the buttocks that rotates the leg outwards. It runs from the base of the spine (the sacrum) and attaches to the thigh bone (femur) roughly where the outside crease in your bum is. The sciatic nerve runs very close to this muscle and in some people (around 10% of the population) it passes straight through the muscles' fibres! If the piriformis muscle becomes tight it can put pressure on the sciatic nerve and cause pain which can radiate down the leg, commonly known as sciatic pain (see sciatica). It has been suggested that this condition would be better referred to as piriformis impingement due to the impingement of the sciatic nerve.
A common cause of Piriformis syndrome is having tight adductor muscles (inside your thigh). This means the abductors on the outside cannot work properly and so put more strain on the Piriformis.
Symptoms of piriformis syndrome:
Tenderness in the area of the muscle.
Pain in the buttocks.
Pain which radiates down the back of the leg, usually into the hamstrings and sometimes even the calf muscles.
It is common for pain to initially be confused with a hamstring strain or hamstring origin tendinopathy. However there will be no area in the hamstrings which is tender to touch.
Reduced range of motion of the hip joint, especially into internal hip rotation.
For those who have Sciatic issues, go to a sports massage therapist and suffer no more, same for those of you with shoulder pain. Don't forget you are constantly tensing your muscles while you are doing your job.
Martin