Is it a sharp pain in your buttock?

Because you were doing some bending/standing/bending type movements, I wonder if you have sciatica?

If you can.......
* Lie on the floor close to a chair/sofa.
* Move your buttocks towards the chair, so that your buttocks are almost touching the seat.
* Bend your knees and rest your leg from the knee down, on the chair.

Your body should now be in a "Z" position.

If the pain eases, then you most probably have sciatic pain as this position removes the pressure on the spinal nerves.

Here's a link that describes sciatic nerve pain:
http://en.wikipedia.org/wiki/Sciatica


PS. There are other conditions that will cause buttock pain, but sciatica is by far the most common reason.