It honestly sounds like you had some impingement and the rotator cuff tendonitis was just kind of there... or it could just be both.
Total rest is generally always not very good... always good to do some type of mobility work with it if at least getting it moving in non-painful ROM.
I'd start out with a week or so (2-3x per week) of just the rotator cuff exercises and see how that feels.
If that improves I'd add in some more stuff such as some LYTPs and such.
Have you tried using a tennis ball et al to work on the muscles on the back of the scap and rolling out your lats/chest/etc. as well? Might want to see if that helps as well.
Ice if it helps too, yeah. NSAIDs maybe if you wanna try