I must say, you do owe it to yourself, passengers and crew to discuss this with a medic, 'specially if it could interfere with your flying. I guess that this is a common problem for pilots.
Ok lecture over now. It does sound like sciatica, although diagnosis by internet isn't ideal. The problem is likely to be in the lower back, but the nerve pathways get a little confused, and the brain can ends up thinking the problem is elsewhere-big toe, knee, buttock being common sites.
Your quack will be able to take a detailed history, and depending on several factors, it may be best to take a "watchful waiting" approach at this stage-often things settle on their own.
There are a number of conservative options (pills) which may help, but again, you really need to take expert advice. Some of the treatments may affect your ability to fly. (eg codeine, amitriptyline.)
Unremitting/persistent cases may require further investigation and treatment. There is some fairly robust evidence for chiropracty, (probably more so than for physio).
Surgery, I would suggest, is a last resort.
PS, just re-read your post- when you say "swollen" do you mean its red and inflammed, or just a funny shape?