A: Initially we need to determine what kind of pain we are discussing. Is it a sharp stabbing pain, a deep burning sensation, or possibly a quick traveling pain through your leg?
For sharp stabbing pains you should check your seat cushion for anything that might be on or sticking through the fabric that could be jabbing into your flesh. This could be small splinters, toe nail clippings, or even really tiny knives. If the seat cushion is free of sharp objects you should check your pants for those same pointy items that might be caught in the material.
A deep burning sensation could be caused by overworked muscles, or even muscle tears. You should try to stay off the leg and get plenty rest to allow the muscles to heal. If you absolutely must get up and move around you should get a pair of crutches and costume leg cast or brace. If you are going to slow down the healing process of your leg you should at least get some sympathy out of it. You could probably use it to impress some people at the local bar with tales of your secret life as a spy and how you sacrificed your leg to save the world.
A quick traveling pain through your leg could indicate any number of hard to diagnose problems. I would advocate removing the leg. It would save a great deal of time and wasted effort trying to identify the cause of the problem when the pain can be eliminated altogether. No leg, no pain! This method of treatment is extremely effective in all areas of the body except the head and torso. I look forward to the day when we can transfer our brains into artificial bodies (Reminder: add to research queue), which I would recommend happen immediately at the point of peak physical maturity.