Too Early to Switch Formulas? Advice!

My LO is a week and 4 days old. Combo fed in the hospital and switched entirely over to Similac 360 RTF last Monday. The past two days LO has been extremely fussy after feedings during the day. Today he was up for 3 hours with a small 30 min nap and finally knocked out in the car seat when I went to pick up his brother. So far, night has been ok (knock on wood). He's currently in a baby wrap on my chest passed out.

I mean nothing is settling this child. It's like he's uncomfortable no matter what I do. I use Dr Brown wide nipple bottles and pace feed. Burp after every oz. Right now he's ranging from 2 oz to 3 oz. He does drink extremely fast so I've ordered some preemie nipples to try. I've noticed he sometimes gags after feedings arches his back, maybe gassy (I've always been bad at telling if they are), and seems like he's always hungry. The ped didn't seem concerned at all and just said it's normal and there was no need to switch formula.

Anyone else experience this or have insight?