Thanks for your patience and sorry for my tardiness...
The shoulder sounds like you may have stretched the capsule of the shoulder joint. The capsule is a thick fibrous bag that covers the joint, giving it added stability. You may have stretched it, which caused a minor subluxation (not dislocation). You should get this checked out by a doc or physio to make sure the joint is stable. It should heal ok provided you don't stretch the capsule for a while, which means avoiding end of range movements (like a pec stretch). Keep your reps partial and close and do lots of shoulder internal rotation work. Again, seek advice from a physio.
As for your other dilemma, while you've been training for about 4 months, this is still a short time, and you've varied your training around a bit. I would suggest getting back to basics, compound movements, lower your reps, increase the weight, and then chop it around and do higher reps and drop sets to max out. I'm sure you'll get a lot of advice on here and I'd really appreciate MO's input to your problem.
I would also like to see what supplements you're taking, and you really need to get some quality protein into you in the morning, and more before bed with some peanut butter. You should also be adding some creatine there, particularly PWO.
Over to the troops.
Let us know how you get on with the shoulder.
BD
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