I too have tendonitis in my left elbow...The so-called tennis elbow, from playing too much electric guitar that I bought in June. Too much bending steel strings and damping did it for me. It's been 3 months and don't practice at all but play during my guitar lessons. I teach classical guitar and should know better than to over do movements like bending and damping. I go to a physiotherapist who gives me heat-treatment while massaging the area and acupuncture with electric pulses (fun to watch). He also tells me to stretch my wrist while I massage around my elbow. There are various lotions you can use, like what sportsmen get, and also using wristbands could help. I've heard tendonitis can take a long time to get rid of. Best of luck to you!
Kevin Aram "Torres", 2009
Stephan Schlemper "Transparence", 2015
Whatever you can do to have a good time, let's get on with it so long as it doesn't cause a murder...FZ