I don't know exactly what is causing the pins and needles feeling but as you correctly stated, the extra 100 pounds you are carrying is going to make any problem that much worse. You never mentioned what your diet is like, but I would think that you would feel a whole lot better if you lost some weight and were on healthy diet. It sounds like you have insurance so I would suggest getting as many tests done as you can. Even if it doesn't help you solve the mystery, you will have them down the road as a reference to compare to.