My son had GERD starting at 4 months old. He would spit up all the time - even when he hadn't eaten or drank anything for hours.
The dr. put him on Zantac for a year, which he had no problems on. The GERD continued and we saw a gastroenterologist specialist. At age 2 they put him on Prevacid, which is stronger than Zantac. Again, medication was fine and by the time he was 3, the reflux was under control and he went off all medication.
My son is now 5 1/2 and he burps often and sometimes his food comes back up. I am keeping a close eye on it, because if left alone, this could lead to esophageal problems. I'm not trying to scare you, but please pay close attention as your child gets older.
Hopefully your son will outgrow this soon. But don't turn away from Zantac if your dr. recommends it at some point. You don't want damage to form on his esophagus. Again, this takes years, but you want to be in tune with him down the line.
Hope this helps.