A few years later and I am very very happy to say that I have not had any problem with my tendonitis since the time of posting the original message.
I tried Trigger Point Therapy with some success, but I believe the crucial factor in my recovery was one-on-one Alexander Technique lessons in my music conservatory - for a period of about three months, I attended weekly. I have not had any sessions since then (almost four years ago), but the lessons learnt then have become embedded in my piano-playing, and as stated above, I have not had any reoccurrence of tendonitis. I attribute this in full to the AT.
If anyone is interested in learning more please ask. Suffice to say for the moment that through the AT, i learned that I had previously been playing with a lot of tension held in my arms, wrists, back and neck (and possibly elsewhere too, such as areas of my back), and that it was the force exerted on my tendons through playing while tense which caused the injury.
I learnt to relax completely while playing. This took some time, and would almost be visually imperceptible to those uninitiated in the AT, but as well as allowing my tendonitis to completely heal while still playing, and preventing it from reoccurring in four years of intense practice, I believe the AT also improved my sound at the piano, and my musical interpretation.
Again, if anyone is interested in learning more please ask, or research the AT.
As a full-time classical musician, I highly recommend it.