Gripe water works wonders

If it doesn't you can also just try to burp him until he does burp. Maybe lay him on his belly on your legs to put pressure on his belly

Okay @andrewsmommy hope it works .

Get gripe water or for the moment lay him on his back and take his little legs and push them lightly into his belly like when you were giving birth. Hold for 5 seconds and release. keep doing until he let's some gas out