Shoulder impingement is usually a movement problem
Pain at the top of the shoulder when you reach overhead is rarely about the joint itself. It's about what the shoulder blade fails to do.
A pinching pain at the front or top of the shoulder when you lift your arm overhead is one of the most common complaints in any gym. It gets labelled impingement, people are told to stop pressing overhead, and often nothing improves.
What's actually happening
Raising your arm fully overhead requires roughly 60° of upward rotation from the shoulder blade. The arm bone can't do it alone. If the shoulder blade doesn't rotate — because the lower traps and serratus anterior are weak, or the pec minor and lats are short and holding it down — the top of the arm bone runs out of space and compresses the tissue underneath.
The tissue that hurts is a symptom. The scapula that didn't move is the cause.
Quick screen
Stand with your back flat against a wall, ribs down. Raise your arms overhead keeping the backs of your hands on the wall and your lower back flat. Most people either can't get there, or can only get there by arching the lower back — borrowing range from the spine that the shoulder didn't have.
What to train
Wall slides teach the blade to rotate upward under control. Prone Y raises and face pulls build the lower traps and external rotators that hold it there. Then earn the overhead position back gradually under load — the range you restore has to be strengthened or it won't stick.
Note the order: control first, then strength, then load. Loading a position you can't control is how the pinching started.
When to stop reading and get it looked at
Pain that wakes you at night, weakness that appeared suddenly, or an inability to raise the arm at all needs proper assessment. A rotator cuff tear does not train itself better.