For A Few Years Now, I've Had Moments Where Such

For a few years now, I've had moments where such a sharp pain would run through one or both my thighs, that I cant move. Mostly it is when I am getting up from bed or a hard surface. I have seen a huge improvement since I became more active by walking to and from work 4 times a week. I am still curious as to the horrible excrutiating pain which I still get once in awhile.