I had "sciatica" about a year and a half ago.
First and only time I have felt this type of pain. Scary.
It just appeared, spontaneously, after getting out of bed one
morning, and walking up a short steep hill to go to work.
Then bam!, it hit me.
The pain waxed and waned, sometimes bordering on
debilitating. I stretched, got sport massages, OTC pain
relievers, heating pads, ice, etc . . . nothing seemed to
help, make it better, or worse.
The therapist I saw (it felt worse after treatment) said
I should consider myself fortunate, some people she has
treated could barely walk. Now, mine wasn't that bad, I could
and did still work out but I had to be very careful of sudden
movements (that would trigger it), but it sure hurt like hell,
and the pain, tingling, running down my leg was a totally
new sensation, one I hope I never have again.
Then, as quickly as it arrived, it went away. Presto. Magic.
Can only tell you what happened to me and suggest that
you try and figure out that isn't caused by something structural
that you could make worse by neglect or overuse.
If you haven't checked these out, a couple of good links I think:
http://en.wikipedia.org/wiki/Sciatic_nerve
http://www.spine-health.com/conditions/sciatica/what-you-need-know-about-sciatica
http://www.medicinenet.com/sciatica/article.htm
I'm sure there are others. Hope this helps and you find relief.