What Causes Pulsating Sensation In Legs?

Hi I have been having this strange sensation down my legs. I first noticed it when I sneezed while sitting at my desk. It was this strange pulsating sensation that went all through my legs down to my toes. It doesn't hurt, it just feels like a pulse that shoots down to my toes. It occurs when there is a pressure from my abdomen. Like a cough or a sneeze or just blowing. I have had it for about 2 months now. I'm 32, 5'11", 140lbs. I'm not that physically active. I'm healthy, but I do have hypothyroidism.