For 2 weeks I've had a sensation of dampness &water on my buttock/outer thigh but there is nothing there. It was there months ago, went&now back again?

Nerve. This distortion of sensation sounds like a patch of irritable superficial nerves in the buttock area and thigh. A demyelinating process such as seen in multiple sclerosis is a possibility. A neurologist is best qualified to evaluate this symptom.