Doing exercises that focus on the "eccentric" contraction of the elbow extensors will make the tendon strong and healthy again.
Do some research but using an elastic theraband works well. And do a lot of ice cup massages (1-2 minutes 10 times a day if possible). Make them with 5 oz. paper cups.
Google some of the terms I mentioned if you are unsure what they mean.
best regards.