Ice only works initially when there's inflammation, but it prevents healing thereafter. Cortisone shots just mask the pain for a couple months.
I tried prp, cortisone, PT (everything but surgery, which is what the orthopedic surgeon was suggesting), while playing lefty over a year w my sons. Luckily, they were young so it was still competitive.
Any impact hurt. Hammering, etc. One handed backhands, in particular.
Ultimately, you need to break up the scar tissue, which is causing the pain.
Look up fascial manipulation. Basically, deep tissue massage for multiple consecutive days. I dug in the top of my elbow w my thumb for an hour or two per day for about 5 days. Immediate relief. Heard this from a guy who couldn't even hold a glass of water. Did this a few days and was good. He heard this advice from a former stuntman, haha. Corroborated by someone who has posted on the internet quite a bit about tennis elbow, if you research TE.
Started by hitting 2hbh, then eventually back to OHBH. Flexible racquets (I only use RA <60), natural gut (I use a hybrid), low tension. Now I can swing out as hard as I need to keep up w my older teen as he progresses. We recently beat a former D1 (30-something) and his partner in straight sets.
Recovery is possible. Good luck.