If there is tendinotis there is an inflammation and anti inflammatory drugs and rest will make you feel better. If there is tear of RC then doing exercise or doing massage and heat will not do anything.
and if there is tear, which will cause inflamations and you do not want to heal it or doing massage. those will make it worse. you need to ice it if there is inflammation.
you might have a partial rupture
I would like to hear from you after the firstMRI appointment.