Geez!
That could be serious, better get your Doc to check you out
ASAP. Playing bass is relaxing most of the time. Sounds a little like an irritated or a pinched nerve there.
I also once thought I had an issue with a broken neck, but my luthier assured me that the truss rod was just "way off".. so problem solved..the pain miraculously disappeared the next day when I picked up the P-bass.
