An odd arm issue I get when training with my sword in kung fu?!

An odd arm issue I get when training with my sword in kung fu?

Alright. First of all I know its not the sword because it is a special ultra light one that weighs less than a pound. Anyways what happens is sometimes when I swing in an outward motion with my right arm as hard as I can my shoulder will temporarily dislocate. At least thats how it feels. It pops right back in as soon as the swing is done but it become unhinged for a second and its massively painful. Anyways I wanted to ask what may be causing this and how I could stop it.

1 month ago
Thats the thing. Its not really a dislocation as much as it is close to one. It unhinges but not fully. I dont have to pop it back in. Do you know a way I could fix this?

My second son has the same problem. He has dislocated his joints many times. It's a condition.