yet another playing pain type of thread

[andrewd]

Last week I practiced my bass almost straight through for a day (my final exam proficiency was the next day and i was nervous!), and since then my upper arm has felt very sore. I didn't play for three or four days, but it was still there. It's so prevalent that I haven't been sleeping well. I can play fine but then the rest of the arm starts to burn. Am I just not used to playing so frequently? My band has been having 3-4 hour practices every day for several days, and we plan on going until at least our gig Friday.

edited to add that this is my left (fretting) arm. I play a Carvin 6 string and I'm usually pretty good about keeping my thumb on the back of the neck, not the side.