I had something vaguely (very vaguely) similar happen a bit after I started taking progesterone. At around that time, I started getting a random stiffness/weirdness/almost-pain at the front of my right leg, maybe a third of the way down. It did feel a little bit like a muscle cramp, but localized to a very specific (and consistent) area. I only ever noticed it when walking.
Touching and massaging that area didn't hurt or feel any different, and there wasn't anything visibly different either, other than it being the location of a fairly noticible vein. Since it wasn't a particularly strong sensation, I never went to the doctor. In the end, it just kind of stopped happening at some point.
This probably isn't that helpful to you, but wanted to describe my experience since it at least had a couple things in common!