Pins and needles is describing nerve pain. Perhaps you have a pinched nerve or are aggravating a nerve when you are exercising. I would let your doctor know, as it may get worse if you continue.
When I do any short intense exercise such as a bench/bicycle crunches I have to stop because I get a painful sharp pins and needle sort of pain and you can even see bumps! I have been doing these for years with no pain. It's on my upper back&chest?