TY! In my case the pain appears when I reach for a computer mouse. I first thought its due to serratus not working due to LTN getting caught in the scalenes. Since this is where the rhomboid and levator attach and both hurt if serratus is weak (unopposed), but then I realized that even though I seem to have got my serratus working somewhat, and can raise my arms now, this pain is still there at the exact spot.

Another thing is I can work with elbows to the side on laptop with horrible posture from time to time, and my shoulders hiked (which would mean Upper Trap is working, right?) but this pain occurs when i work with my hand to the side since my chair has an arm rest located to the sides.
http://www.med.umich.edu/lrc/coursep...r_limb_05.html

This says serratus and upper trap become useful only after 90 degrees.
http://anatomyresources.hsc.wvu.edu/...Abduction.html
Neuromuscular deficit: Weakness/paralysis when abducting at the shoulder under resistance. In normal subjects the supraspinatus initiates the first 15 degrees of abduction along the vertical plane. The deltoid functions from 15 to 90 degrees, while synergistic actions of the trapezius and serratus anterior abduct from 90 to 180 degrees by rotating the scapula laterally. Denervation is accompanied by muscular atrophy, shoulder adduction, ‘winged’ scapula, and cutaneous deficit along the distribution of the axillary (superior lateral brachial cutaneous) nerve.

Another thing I just realized is this always made me feel worse. But this comes up as a supraspinatus stretch too in the google image search!
http://www.teachpe.com/images/jenny/...r_stretch2.jpg

I was trying to stretch my rhomboids since they would be overstrong with a very weak serratus.

So its probably supraspinatus i guess.. is that logical

Question is how to rehab it.