shoulder impingement

I have a slight downward sloping acromion
bicep tendon tendinosis (Intermediate signal intensity)
rotator cuff tendinosis, no evidence of tear
no evidence of muscle atrophy
 
I can't afford a PT unless I choose not to pay my rent, so I'm stuck trying to gain enough knowledge to figure it out on my own.  So I'm asking for you to speculate and I will not take your advice as a specific diagnosis.
 
I tried working on scaption exercises and (doing them correctly not going above 90 degrees and thumbs up orentiation of my hand)
I found that these exercises would cause my arm to hurt worse several hours later meaning that even these exercises are causing pinching of the tendons.  This leaves me very confused.
 
So takeing a step back, what muscle(s) might be weak that could cause impingement even in correct form scaption exercises? "

 

Ask a PT Response: "Scaption is a combination of abduction and flexion, thus there are a variety of muscles which are involved when producing this movement (ie. shoulder flexors, abductors, & external rotators along with scapular stabilizaers). Weakness may not be the only contributory factor involving impingement. Impingement can be contributed to a number of factors including structural abnormality, ie. slight downward acromion (Type II & III shaped acromions), hypermobility at the shoulder joint, poor joint arthrokinematics, instability at the shoulder joint, postural deficits, poor neuromuscular control, etc. Identifying what may be contributing to shoulder impingement is extremely important in order to develop a plan of care and to maximize outcomes."