Hi Davo! I had/have tendonitis in my arms and elbows, and just eating according to basic primal guidelines really helped. It took a few months to start feeling the difference, and it still crops back up if I really over-work them, like digging fence-post holes or something like that, but as long as I stick to no grains and low sugar, the pain goes away after a few days.
There are other members more up on info on omega 3/6 ratio factors, but from what I've read, some good quality fish oil supplements can be helpful as well, so maybe they'll speak up.
I hope this helps, though!