Is this reflux?

I have a premature 3 month old. Sometimes he has these moments where he’s turning red. Flinging his arms like something is wrong. Spit bubbles start forming at his mouth. And he’s arching his back and it’s very scary. I used to think he was choking but after reading some things I think he has reflux. Some nights he cries . The longest would be 3 hours straight of on and off crying like hell stop for bout a few mins a cry again but eventually go back to sleep for a decent stretch sometimes he gags out of nowhere too what do u guys think?