Ok, really good you figured it out earlier on and have seen improvement. There seem to be lots of variations on it, some people get it due to a forearm imbalance, where strengthening the wrist extensors does the trick, some people have knots in their forearms or triceps that put a constant tension on the tendon, and some are just straight up tendon damage like what I did.
I did p.t. for about 6 weeks where they also did some ultrasonic stuff and graston massage on the tendon. I think it helped, but didn't seem completely necessary. It sounds like you're doing some exercises for it which is good, I always did 3 sets of 10 to 15, but making sure never to go to the point that it was aggravated at the time of excercise. Maybe add some rotational stuff both ways holding a hammer, and look up the theraband flexbar.
I think elbow revive has helped a bit, but it may be a placebo. There can be lots of plateaus in the healing process, sometimes for a month at a time. You just have to be patient and keep working and stretching. Lots of good stretches, just search around and pick a couple to do 3 sets of 30s every day.