I’ve had this throat issue since I was a teen and like your son went through what you call melting which eventually stopped happening. Also have stretch marks on my back from growing fast. The way I pop it back into place is tiling my head way up and then down, I’m sure it’s not the same for everyone. I have many indicators of having some form of marfans symdrome, you can’t tell by looking at me but some of the things have always made me wonder if I have it. Symptoms include protruding sternum, stretch marks, mitral valve prolapse, doubled jointed.