Do you keep him upright after feeding? Try that and see if it helps. Has he been checked for a tongue tie?You can also elevate his cot a tiny bit so his head is just a little higher than his feet. Of all that doesn't help, ask if something like Infant Gaviscon could be used occasionally.
Ask your doctor if you can try thickeners. Keep baby upright for 30-45mins after each feed and you can also elevate the head of their bassinet/cot so they aren’t completely flat (I used a wedge under the frame)
i woudlnt recommend gaviscon baby milk thickner like others have suggested, my girl has bad reflux and that gaviscon just made her so constipated it was awful! I breastfeed and express to use a bottle. When using a bottle we burp her a couple times during the feed as well as after, then we hold her up for 20-30 mins upright and we try not have her directly flat on back during day. Her clot was slightly elevated like soemone said above but it isn’t now as got advised not to do that too but i’ve found that at night time i just feed her and then will hold her for longer period of time so when putting her down she is in a deep sleep and therefore doesn’t tend to wake up or be sick at least in that first stretch of the night between 7 and about 12. I use a sling in the day too for a least one nap as find that helps cause otherwise gets overtired and won’t settle for longer than about 20/30 mins. I can’t recommend any formula but these are just things i do that have slightly helped :)
Mine daughter was same. I start put some carom seed(ajwain) in water and boil it properly and then strain it. I made her formula milk in that water and she is much much better now.