Calvin Klein syndrom. This sounds like meralgia paresthetica, also known as "calvin klein syndrome." the problem is caused by the nerve that provides the feeling to the skin of your thigh getting pinched by a tight wasteband. This can happen with super-tight clothes (super models wearing calvin kleins) or with a large belly overlapping the waste-line. The solution is to reduce the pressure on the waste.
Is it outside? Is this more on outside of thigh?If so, it may be meralgia paresthetica, a problem with the lateral femoral cutaneous nerve. Seen often after pregnancy, with abdominal obesity or tight belts, it's caused by pressure on the groin. Wear loose clothing and relieve pressure and it should improve. See your doctor for diagnosis and to rule out other things.