My boys both developed similar symptoms at a much younger age (4 weeks and 2 weeks respectively). The first one (now 3.5) had both reflux and gas, same with the second (now 2). We used generic gas drops (Infant Mylecon is $$$) and Zantac (prescription) for both of them. For DS1, it was definitely the Zantac that made a difference, and by time he was 4 months old, he'd outgrown it. With DS2, it was more a gas issue in the long run, so by time he was a couple months old, he'd outgrown the need for Zantac but not gas drops.
I'd try using gas drops first. If that doesn't make a difference (or not a big difference) after a week, I would ask your pedi if you could try a short-term Rx for Zantac (perfectly safe for babies, btw) and see if it helps. For us, we had to try both, and both helped, but with each boy it was different as to which was the actual problem and which "cure" worked better.
Also try to consider whether there has been anything new added to your diet or if you've changed formulas--either can cause a reaction in some babies if they have a sensitive stomach. If diet has remained perfectly constant, gas or reflux are the likely culprits.
The good news is, whatever your son's real issue, he will very likely outgrow it, providing it IS just gas or reflux. My guess is reflux because of the pre-spit-up discomfort/fussing.
Good luck!