I'm surprised you can pin-point the sudden onset of pain/issue to a specific event & time, yet the diagnosis is a gradual process type injury/issue where you would have notice the increasing discomfort over a period of time.
If you still have the MRI scans would you not consider taking these to a sports injury/specialist/physician?
In 2009 I injured my right shoulder doing Bench Press (trying to press 180kg to shoulder line when usual line is to nipple/sternum line does NOT work.....IDIOT for even trying!!!), my GP prescribed Voltaren, a few physio sessions & suggested I take a break from training.
Long story short, after repeated insisting to the physio that the issue was not resolving I was given contact details for a specialst sports physician (deals with those insane blackout-before-I-tap-out-MMA's & rugby players).
A relatively in-expensive CT scan confimed I had a tear in my Suprspinatus Tendon. Further investigation by MRI confirmed a full depth tear of 60% the Suprspinatus Tendon, 20% tear of the Infraspinatus & 20% tear of the biceps tendon at the Supraglenoid insertion. Surgery was the ONLY option.
Now 2 years & nearly $30k later (quite pricey for 5 stainless anchor screws!!!) I'm back in the gym doing what I enjoy with every intention to lift heavier than before.
My point being don't give in to accepting a diagnosis if you feel more investigation is warranted. Go to a specialist for comprehensive, hands-on assessment & diagnosis. I strongly doubt anybody, regardless of their good intentions/similar experience could do a diagnosis by reading a forum post.