Title of thread caught my eye. Since most have offered a way to take the stress off of your arm, I'll respond a different way.
I used to play tennis about 5 times a week. About 12ish years ago, I developed tennis elbow - my doctor prescribed rest and wearing a strap. Of course, I continued to play and had the tennis elbow for about a year. Near the end of that year, I came down hard on my foot, playing tennis, and got plantar fasciitis. After a few days of limping around, I went to a doctor who told me to take 4-5 ibuprofen 4 times a day. I was hesitant at first and didn't take that many the first few days, but then I did. The pain in my foot went away and without even realizing it, the pain in my elbow was gone and I haven't had it since! I'm still pretty active with tennis and golf, as well as other physical activity (light weight training, pickleball, splashing around in the pool.) Ibuprofen worked for me.