Have you ever considered eliminating gluten from your diet to see if this helps resolve your joint issues? This helped my son and I when we were having similar problems with our joints.
I have already eliminated gluten from my diet after finding that it causes me to breakout. Also, oats worsen my keratosis pilaris, so I do not eat those.
My diet already has the following eliminated, but I suspect I should eliminate more:
corn, wheat, oats, nightshades, apples (cause severe nausea), garlic, onion
I have been eating almost exclusively from this list:
brown rice, lentils, zucchini, red cabbage, cucumber, melons, bananas, beets, carrots, fennel, and some various spices.
I'm a bit worried about this chronic tendinitis because it has been going on for so long (15 or 16 months at this point). I now have tendinitis in my wrists and my right knee and left hip hurt when walking. My right knuckle pain and swelling reduced once I cut out tomatoes and potatoes, but it is still not back to normal, so I suspect there is something left, and I might have to do a radical elimination diet. I'm not exactly ready for such a strict change until next week. I also have the starts of pain in my spine again (I believe another bulging disc).