Newborns don't get tummy ache, don't get agonising pain from "gas". They get HUNGRY
DS1 certainly was hungry. Six minutes into every feed, he would start screaming. Because he was in pain thanks to silent reflux.
Of course, he hadn't had a full feed in that six minutes, so an hour or two later we got to do the whole thing again.
Best bit was, because he was gaining weight, the doctor and HVs didn't give a shit. It was incredibly hard to get anyone to take seriously. Thankfully he outgrew it.
It's a very different cry to the cry of a newborn who's uncomfortable because they need to fart, or who is outraged because you expect them to operate a digestive system. Having a second baby who doesn't have reflux beyond the normal 'let me show you my milk' has been an eye opener.
OP - a lot of the time newborns are just irrational angry little beings. Being part of the world is an OUTRAGE and they want you to know it. If it was a one off episode last night/today, I'd just forget it - your baby was cross for a reason no one will ever know (probably by the end, upset because feeling tired/rubbish from the effort of letting you know he's upset!)
I think there's a developmental leap around this time too - DS2 is nearly 8 weeks and has been fussier this week.
If it goes on, don't rule out reflux or an ear infection. Baby ears are bastards.