I have had tendinitis and tenosynovitis for going on 19 years. It’s in my wrists, started in music school at 18 yrs old from playing guitar, and it all but heals with rest, up to the remaining 20% or so, and so therefore it very easily flares back up with use and activity. After lots of medical digging, I found out I have L-HSD localized hypermobility spectrum disorder, a gene negative connective tissue disease involving the immune system. From my research, the best plan is to get PRP injections into specific tendons where Cortisone injections were previously helpful. PRP is expensive, and because Cortisone is covered by insurance, you can use the corticosteroids as a test. If the corticosteroid gave relief for say 10 days in the tendon an 0 days in another, your best chance is to put the PRP where you had the most relief from the steroid. This is what I was told. I lost my job and have not been able to get the PRP yet, but I’m definitely planning on doing it. It does seem to be the best solution for tendinitis, tendinopathy, Tenosynovitis.