[Blarg]

Your body is not meant to take that kind of pressure forever. I've had episodes like you refer to, to a minor extent, and they went away after a while.

You can also experience peripheral neuropathy from taking too much Vitamin B6.

Whatever it's from, good luck; it will probably pass. But you should seriously reconsider lying down like that much. It can be very comfortable and I used to do it endlessly, but it's just not good for you. Sounds like you've found out, like I did, that those nerves weren't made for taking pressure that way for extended periods of time. Find healthier postures.