Handstand Work Tweaks My External Rotator Cuff Muscle?

lately I've been doing my handstand work for few minutes a day. Whenever I'm in the handstand position trying to practice balancing back and forth from finger to palm, palm to finger; my external rotator cuff muscle doesn't feel comfortable.

 

Today, while I'm trying do the military press, the same sensation kicks in when I holding on to the bar with weights on it. I lowered the bar down to my collar bone and tried to push up, all of a sudden I tweaked the same spot I was describing.

 

Does anyone have any clue of what's going on? 

 

 

The same spot you feel while doing this exercise 

I'd like to see a video of your handstand work and your military press, both zoomed in so that the upper back fills the frame.

 

This does need to be shirtless, or in a sports bra with a narrow back if you are female.

 

Standing posture, as well, would be great, and if you could do slow arm circles getting progressively wider, as well as forward shoulder flexion as well as a lateral raise going straight out to the sides, and then all the way overhead, would be nice too.

 

Push ups also wouldn't hurt.

 

What I'm looking for is how your shoulder blades move. It will be best to see a wide variety of movements.