Could your lo have reflux? I only ask as my DS spewed milk for a very long time. Does your son ever sound like he has a wet cough, especially after spewing?
I always suspected reflux since DS was a newborn, but my ped dismissed it. I brought it up again after we had a chronic cough for 4mo once he turned a year. Started as whopping cough, but lingered and they gave DS antibiotics - didn't work. Steroids, oral and inhaled - didn't work. Finally I demanded reflux meds and it disappeared along with the spewing that occurred almost every night, if not every feeding.
Not trying to scare you, but just giving you something to think about.....