[Sarah.]

That happens to me on some occasions. I remember once I was sitting down and then I tried to move but I couldn't because it was so painful in my chest, i couldn't move for almost an hour. I tried breathing into something, like I put some clothing over my mouth and breathed slowly (dunno how to explain it properly lol), and it went after a bit. I hate it. I never went to a doctor either so I dunno what it is.