Scalene muscles, infra-supraspinatus and potential C nerve damage?

Background:
Being an idiot at 20 years old, very drunk, gloriously slipped and hit the ground with an outstretched arm on my left hand side. Some minor discomfort but nothing major, soon faded. Prior to this I had been in a car accident and had severe whiplash and my left leg crushed causing deep vein thrombosis.
Get back in to the gym for rugby pre-season, perform squats using the close grip on a low-bar position followed up by a push day. Next day I feel a searing pain in my left shoulder blade, go to the doctors who perform an x-ray and see no obvious bone damage/dislocation so give me some medication and tell me I'll be fine.
I ease up on training push exercises, assuming this was what caused it I make an additional concerted effort to bring my rowing strength up to the same level as my push along with performing more rotator cuff/rear delt exercises. Pain still persists, still isolated to my shoulder blade.
Finally get a physio referral, he tells me to perform exercises to "open the shoulder blade up" and performs some myofascial release that makes me feel better for about four weeks and then it just hurts like hell again regardless of how many of his stretches I make.
I stop squatting over summer due to a leg injury and my shoulders actually get slightly better (I didn't make the connection at this point), along with getting my housemate to walk on my back whilst I laid down I felt releasing around the thoracic section of my spine and this would help. Pinching my shoulder blades together etc along with all this certainly alleviated the pain.
Since coming back from travelling I have taken up office work and a daily commute which isn't helping matters, I began squatting again in the low bar position and then it clicked this was causing my shoulder to hurt. I am going to try front squats going forward and see how I respond to them. If I perform particularly heavy pushing movements I can feel a dull sensation in my shoulder blade and bench press feels uncomfortable all together so I avoid it (strangely the overhead press/incline are relatively fine which surprised me as I expected the additional load on the anterior to make it hurt more). I have no issue of rolling shoulders/apt/strength imbalance and assumed if this was the case both sides of the shoulder would hurt anyway.

Symptoms:
-Shoulder blade pain
-Chronic trigger points in my infra/suprasinatus, if I open up my shoulder blade and roll around on a tennis ball against a wall it literally sounds like popping bubble-wrap
-Rolling left shoulder forward there is a series of crackling sound, non painful though
-When performing vertical pushing/pulling the left shoulder comes out of position and will be higher than the right
-Tight lat/teres minors on left
-if tilt neck right and roll back with head or so pulling it further away I experience a load crack in around the back of my neck.
-especially in morning, I can hear a grinding sound in the back of my head
-squats make it hurt, anything to do with spinal compression?
-dull pain in tricep
-my left hand grip strength has deteriorated slightly, little will make it improve.
->90% effort deadlifts cause left-sided lat pain, anything pushing causes shoulder pain. I have to work really hard to experience any substantial progress in pulling movements.
- chest pain when sat down
- the symptoms etc are certainly worsening, myofascial release is just like "filling up a tank with a leak that's getting bigger", I'd like strengthening exercises/stretches that could fix this imbalance or whatever it seems to be. It's extremely hard to get surgery from our NHS over here and private is exorbitant.

I used to play rugby at a fairly high standard and have had to cut back on game time/playing in my preferred position due to this injury. I also have taken up a career in finance and the pain has proven to distract me in the workplace before. Finally, I don't want to only do leg presses I want to squat and deadlift heavy.