I've got pain in my wrists, right elbow and shoulder, from guitar and bass playing I presume...usually flares up around a half hour to twenty minutes of playing in my wrists...spend a lot of the day typing and tendinitis runs in my family...so this is basically a preliminary assumption.
However, I have most symptoms of tendinitis from webmd.com and having the inflamation wouldn't surprise me in the least...I don't warm up well. I see the doctor on Thursday...but so far everyone I've spoken to tells me to rest my wrists as much as I can...not play guitar so I packed up three basses, two electrics and an acoustic...wrap my wrists when not using them and when pain is severe to take Ibuprofen. Among these people were two general practice doctors and three bassists.
I'm not too excited about not playing guitar for about a month, but I don't want to suffer from more severe tendinitis than I have to...so I've packed them up...cancelled all engagements for the month of May, and have my fingers crossed for everything after that.
But the optomist in me won't let me give up...I ordered a diatonic harmonica and I'm gonna let my lips do the work for a month

Hope for the best, as am I and I'll keep you guys informed on the hopefully good news.
By the way, do any of you have any warmup routines you wouldn't mind sharing?