Tendiitis

Having tendinitis yet again is really making me question the viability of doing this as a career ... I don't think there is anything that I'm doing wrong technically/posturally (if... it appears to just be from over-practicing & demanding too high of a standard of playing from myself (relative to my ability level) & also from increasing my practice time dramatically in the span of about a week and a half (from almost not practicing daily to 3-6 hours per day)

It's just very frustrating, because everytime I seem to be making substantial improvement I run into this roadblock ... it's also frustrating, because before that first time I got tendinitis in college (from doing yoga) - I never had a problem with this (and I used to play 3-6 hours every day then too)

I know I'll find a way to get through the concerts I have this week & all the way through the Quebec gig in the middle of may (assuming this even lasts that long, which I doubt it will) ... but I'm really scared that I'm going to keep running into this & I just don't know what to do about it ...

Maybe part of the solution is mandating 2 days a week where I don't physically practice no matter what ... or setting some other cap on my practice time ... but on the other hand, I know there are people who practice 4+ hours daily who don't seem to have this issue, so why do I??? And more importantly, how do I overcome it?