If it happens again, take a needle and a lighter and get it red hot and poke a hole in the nail. Trust me. I heard of it and was like 'yea fuck no'. It took me a day of not wanting to try it but the throbbing and pain is instantly gone when you relieve the pressure.

You don't feel it at all either but it is a little intimidating. Did it with a chair in college, went to scoot up and the actual seat pad came up and I sat on my finger between the chair frame and wood on the bottom of the cushion.