I really feel for you, having golfers elbow is pretty miserable. It's usually the result of an imperfect forehand and/or serve technique, often combined with not being physically toned up enough and possibly further aggravated by using harsh equipment - stiff racquets/unforgiving poly strings.
I had golfers elbow throughout the whole of 2014 and 2015, playing once/twice a week was pretty painful and often I wouldn't even bother trying to serve at all. I played through it having regular dry needling sessions which did help. The crux came when I retired in April 2016 and wanted to start playing 3-4 times a week. This was simply not possible to even hit a forehand let alone a serve. In May of 2016 I had to do something about it properly or give up playing altogether.
I spent a lot of money and went to see a sports doctor, two surgeons, 3 physiotherapists and had a number of MRI and ultrasound scans. It was 50/50 whether to go for an operation. I looked at a lot of other alternatives PRP etc. I refused to consider cortisone injections. I wanted to solve it properly not just mask over the pain with cortisone. I had to stop playing for 9 months but was lucky to meet one physiotherapist who was very frank with me and fortunately had a gym on site. She told me that I was simply not physically toned enough for the standard I was used to playing at. When I did some of the exercises with light dumb bells she said I was cheating on the way I was lifting using my elbow to perform instead of slow correct form. It was a real wake up call. Fortunately being retired I had the time and was determined to play again and even try to improve. Giving up at 56 years old would have been a personal disaster. I love playing (not competitively but drilling and having a good workout a few times a week)
So, I spent 10 months rehabbing and gradually get a bit stronger and more flexible with stretch bands, light weights. I am a real enthusiast and still get lessons. When I restarted in March 2017, I tried to change my technique, increasing the follow through on my forehand and my serve trying to avoid swatting/pushing and making both shots more fluid including after impact. I also tried to not be so open when making serve contact, especially on a first flat delivery. However this is habit formed over a couple of decades.
In order to explain the above better I attach a link to an old video I made at the end of 2015 where you can see the technical issues I am sure contributed to medial epicondylitis i.e. mid way through the video with the forehands when playing a cold wet day outside. On the serve just after 5 minutes and at the end of the video from just before 7 minutes until the end.
During the last couple of weeks on the serve, I am currently trying to stop the racquet lagging behind the toss and get both more in time together. Difficult to teach an old dog new tricks but I can feel it's more comfortable on the triceps, elbow and shoulders. If I notice anything untoward I immediately focus on it.
I kept my equipment the same. I have played with Pro Kennex racquets for 20 years and string them with a full bed of natural gut at a relatively loose 50 lbs. I use the KI5 PSE racquets and when restarting I tried an identical but 10% lighter Ki5 racquet. Ironically when restarting I actually found the lighter racquet gave more twinges than the heavier frames, consequently I am still using the KI5 PSE racquets.
When you don't play and get better you can do other things such as learn to balance better with a bosu ball on your non dominant foot, learn to juggle improving your peripheral vision etc. There are quite a few things you can do so when you return you will hopefully play even better.
As I am a senior I now try and spend a good 30 minutes warming up and warming down after playing plus going to the gym a couple of times a week with stretching and some reformer pilates on a machine as well. Unfortunately warming up and warming down does mean a 90 minute tennis session becomes a few hours commitment but I do feel a lot better for it.
Hope the above helps, be patient, nor hopefully get an operation - good luck !!!
https://www.youtube.com/watch?v=BQ6SqH5QLaE
HDTV 1080p Dec 2015 Bromley Indoors & Wells House
www.youtube.com