Welcome to a wonderful forum. Everyone here is so VERY caring.
Abasaki gave you some good links to start with.....

The pain you describe sounds aLOT like what I've been dealing with, although my legs don't give out on me.....but your description of that pain sounds so much like how I describe mine....and in the low back.

My Dr said that from what I was describing, it sounds like severe 'muscle spasms' going on. And, like you say, they appear to flare for no particular reason alot of times.

My pain meds don't touch this type of pain, but the stronger 'muscle relaxer' seems to be helping.

Just thought I'd throw that out there.

I hope you get some answers soon
Rae