Few questions:
Where exactly do you get the pain and swelling?
What sort of pain is it? (dull/sharp/consistent or only comes on during movement).
Do you ice it when it gets aggrevated?
Do you have wide shoulders?
Look in the mirror very closely - does the tape of your neck (upper traps) look more or less developed on one side to the other? Is one side thicker to the other?
Can you touch your hands behind your back? (on over the top one below). Is one side more felxible than the other? Is so, where does it feel like the range of movement is being stopped - where is it pulling?
What sort of training do you do for them? There's loads of things to look into here like how you bench - don't flare your elbows out...what sort of shoulder exercises you do - for instance if you do upright rows at the moment - stop doing them!
There's so many things to look at and the shoulder joint is so complex that even experienced specialists can find it hard to diagnose shoulder problems specifically.
--- time is never wasted when your wasted all the time ---