Acid reflux or colic???

So yesterday, my son started gagging but never spit or threw anything up. He’s 3weeks+6days and exclusively breast fed. Then today, he’s been super gassy, fussy, and has been gagging as well It seems like he has a hard time swallowing and catching his breath for a couple seconds after he gags.

I burp between breasts and bicycle his legs. We also started using mylicon. I’m at a loss and I’m worried. He has an appointment on Monday