It all depends on what else you have tried.
I have tendinitis in my shoulder. I have tried months of physical therapy, TENS, stretching, cortisone shots, acupuncture, heat/cold packs and rest. The latter two help the most and self-massage with a tennis ball and muscle relaxants for a good night's sleep. I have accepted that the pain will never be completely gone and that it will surprise me in the middle of the day/night. I personally have not tried collagen supplements, I was not convinced of its effects. But it could work for some, so why not.