Have you had your thyroid checked? Since it doesn't sound like your numbness is from surgery (like a numb leg from where they might have connected the bypass machine) since it is in a few different places and doesn't sound like a deep numbness, (like where your leg tingles or falls asleep type feeling, but just the skin.
It sounds alot like the numbness I get where if you lightly scratch the area you don't feel it, but can feel below the skin..(its hard to explain, but it is a completely different feeling than the numbness tingling I get in my legs and feet from a bad back) anyway I get that in different parts, usually my face and they pretty much decided mine was related to my thyroid problems..which makes sense in my case because thinking back it started the same time other hypothyroid symptons started.
I may be completely wrong, but It might be something to ask your doctor about.