I am 5 weeks pregnant and have been having this subtle sensation in my right upper thigh. i am not having any cramping or spotting. should i be concern?

Probably not: Your growing uterus is likely putting pressure on contents of the femoral sheath. This is a tunnel from the abdomen to your leg that emerges onto the front of the thigh and through which travels the femoral nerve, artery, and vein arranged from lateral (side) to medial. Think navy where y is the crotch. Feel the pulse in your groin to find the artery but pressure on any one could cause sensations.