It could potentially be a growth spurt. I would just continue doing what your doing and it should pass 🙂
My first did this, and it was dairy and soy allergy. It took 3m before anyone listened to me and gave a diagnosis. The dairy in the milk was causing silent reflux (it comes up, burns the throat, and then goes back down). Because there was no vomit, we had no idea how much pain she was in. She would fuss at the breast, latch briefly, and scream. It was awful. Obviously, I dont know if this is the issue with your baby, but silent reflux is definitely worth a consideration/investigation. I cut out dairy, and in the meantime, we were prescribed baby gaviscon and then lansoprazole to ease the acid. She was like a different baby xx
He may be struggling with trapped wind or colic. Maybe try some colic drops with him and some leg/belly exercises to get his system moving (there are loads of exercise vids online). My baby was the same at 3wks too