"self-diagnosing" is unreliable- if even possible on AC separations. When you start talking about "grades" you are talking about some degree of tearing/ separation. I had a grade 3 /grade 4 in 2013 (the grades are a spectrum and not always perfectly delineated) during a mountain bike accident. Had to have multiple sets of xrays done- some required hanging weights from the arm in order to measure AC separation. Family doc thought it needed surgery- surgeon said surgery was possible but probably not advised. Grade 5-6 require surgery, 3 and 4 grade tears are controversial. Surgical repair is usually done via ligament graft (often from the hamstring). I was advised that among active people the surgery often times doesn't hold anyways. Surgeon said given my active lifestyle and career (cop) I would probably waste 6-12 months of inactivity after surgery only to have it re-tear again at some point. He advised physical therapy and letting other shoulder muscles compensate.
Talk to your doc and get a firm diagnosis. The shoulder joint is complex- could also be rotator cuff or other problems. Without knowing exactly what injury you have you risk a dislocation under tension. As far as recovery, pending a doc visit- Back off barbell weight on over head exercises and maybe add light dumbbell exercises in the interim. Give it 2 weeks and test it out with some overhead presses and increase weight accordingly- if pain or instability occurs give it another 2 weeks rest from heavy overhead barbell. Band exercises are nice too when a true tear has occurred.
My shoulders are forever uneven when I have my shirt off and mild arthritis has already set in around the joint (I am 31 yo)- but with time and dedication I got my bench back over 300 again and am confident my shoulder joint will hold. Side note: I went about 20 months without barbell after my AC tear- it was a very very long recovery road. Granted, I am sure a grade I tear will allow for a much quicker recovery.