Impingement Of Shoulder

I have been suffering from shoulder impingement for some while now and have been actively looking for ways to address this on the internet.  There are many websites and lots of pages to choose from plus an abundance of DIY videos.  So which ones do I choose to do?  Instead of just trawling through the internet and doing nothing else I decided to pick out a few and try them to see what happens.

1. Right shoulder impingement.  Lying down elbow out at 45 degrees and forearm down at 90 degrees so palm flat to floor.  Tight on right hand side and left hand side OK.  Tried lying down arm up and pinching pec while lowering over head to floor, pulling arm into head seems to pull more on pec major or pec minor?

2. Also did laying on front, arms stretched out in front of me with fingers locked and twisting side to side which pulls on lower back.

3. Laying face down palms down by sides of head and raising head and arms up and holding position for thirty seconds.  I performed this exercise about five times.  Tried item one again and left hand flaps back and forth like Ace Ventura doing elbow copters!  Therefore, this move allows much deeper rotation and shoulder not lifting off the floor and rotating forwards as much.  Action of right hand shoulder now similar to left hand.

It is clear that I have shoulder impingement but what can I do about this?  I have tried numerous exercises for rotator cuffs and shoulder stability but nothing seems to work for the long term.  I do get positive results in the short term for a few hours but by the next day it is always the same.  There is so much on the internet regarding shoulder impingement, exercises, stretching etc. that it becomes a minefield on which ones to choose.

Further investigation required.