I will try to be helpful.
How do you know its tendonitis?
you will need to be certain you are dealing with tendonitis and not TENDINOSIS or even a partial tear.. The treatments are different and treating one when its actually the other can make it worse.
With -itis you want to reduce inflammation. with -osis you want to causee a little bit then help it heal. But sometimes its itis on a background of osis so have to be careful.
With partial tears it depends on how long its been torn and if its inflammed around it or not. Extent of tear and what the tendon looks like. All this goes into healing it. So many idiot doctors just point to elbow saing you have tennis elbow... lemme inject it.. wear this brace... stretch.. have a good day. When they dont do well thats when i normally get them unless its athletes then i usually get them first thankfully