I hope it's not the stick or technique,considering you've just 'settled down' and gotten comfortable with the PDR. Probably a combination of an old injury, sleeping habits and overuse.
I remember hearing a comment while watching the rome tourney. 20 years ago, players were spending 5hours on court to every hour in the gym/off-court conditioning. Today the ratio is typically 1-5, 1hour of court time to every 5 hours of conditioning. If the rec player could even achieve a 1-1 ratio, I think it would be very beneficial.
I'm pullin' for ya man. It's terrible news to say the least. Even though I get on this forum during my down time (while my other friends are on reddit, facebook and youtube), I still feel a certain 'connection' with all you guys, especially in this thread. I was going to glow about the Vcore100s, but now I feel it is not the proper time. Keep us updated.