What Causes Pins And Needles In Thighs After A Rotatory Cuff Surgery?

I am 58 yrs old, 5'2", 190 lbs, and normally healthy except for overweight. I had rotater cuff surgery on my right shoulder about 3 years ago.

A couple of weeks ago the back of my right thigh felt like a pin was sticking me or a bug was biting in 3 or 4 places. It was painful enough for me to holler out. I went into the bathroom and discovered there was nothing there. Since then, the very painful pin feeling is limited to one place on the back of my thigh, and seems to happen more when I walk, making my pants move on my skin in that particular area. It does not hurt if I am sitting still.