Hey KPj, thanks for the reply.
I'm currently following this program http://www.exrx.net/Workouts/Workout3PPL.html
and on push i use DB presses (Incline/Decline) and a fly (slight incline) and a DB front raise for anterior delts.
OK. All of those are most likely going to hurt. Try doing the DB bench press on Decline with a neutral / hammer grip. See if push ups hurt, too. When doing DB bench press, drop the weight and concentrate on keeping your shoulder blades down and back. If you get into position correctly, your rib cage will pop up slightly and your back will be arched slightly. This is a good thing. Also, don't let your elbows flare out to the sides (90 degrees), keep them tucked, at about 45 degrees.
Another thing is to do DB bench press on the floor (to restrict ROM), with a neutral grip. All the above applies to - elbows tucked, scapula back and down and tight throughout the whole ROM. You actually will think more about your scapula than your chest or shoulder if you do this right. But again, only do any of these if it's pain free and if you can lift pain free, then go for it.
Lastly, I would say in this case, use a tempo just until you get used to it or know it's painfree or not (basically to force you to use lighter weight). Take 2-3 seconds to lower, and 2-3 seconds to press the weight - so that you can make sure you are stabilising via your shoulder blades, and not your shoulder JOINT.
I did see that article on the shoulder blades, i think although not as extreme as that pic my shoulder blades have always protruded slightly like in that picture and i have a very limited ROM on pressing exercises (i.e. i can't come down very low on a DB press, can just about stretch upper arm parellel with floor).
Your internal rotators are most likely very tight. Same with upper traps. Some pec stretches and upper trap stretches will do the trick. But again, only if pain free - you might need to give it a few days / week before you can do anything pain free with the shoulder.
I've only recently (within the last 6 months) learnt the importance of good posture and try very hard to hold my shoulders back with blades pinched together during exercises and generally when sitting at work etc.
This is good! keep it up! You can have the best program in the world to correct posture, but if you don't try and fix it the other 23 hours your not in the gym, then it's almost pointless.
I'm half tempted to drop all exercises that may effect that area and just work hard on all the other areas i can perform (Legs, Abs, Biceps, is back ok?).
This would probably be best. 'Pain Free' is the key. If you can train all of these pain free, then go for it, especially back. But if you can't, you need to just bite the bullet and take time off.
I tried just raising my arm to my side using the other arm for a little bit of resistance and it's very painful. Also changing gear (reaching arm forward specifically with thumb down) is painful.
If you have the means to see a physio, I would strongly advise it. I had a similar thing ages ago and it ended up to be a partial tear... It's always good to get a specialist in their to have a look, even if it is just a sprain.
I know from direct experience, if you can train pain free, then train. But make sure you don't kid yourself, your shoulder will be in a delicate state right now, so be GENTLE with it, whatever you do.
If it aches constantly, then Ice it every few hours. Simple advice but it is effective. Anti Inflammatory cream, like deep heat, is worth buying, too.