I would suggest the foods you are offering him have been cooked in or tainted by Aluminium

even the baby formulae is probably loaded with it

Gagging on food is a classic result of a child who cannot tolerate Aluminium

Check very carefully everything
only prepare food in glass and check with your water supply company what they treat the water with

A good Homeopath should be able to help your babies but IMHE when a baby refluxes or gags or vomits its because you are trying to give them something they are allergic to

Also remove all dairy /milk products for 3 weeks as Milk allergy is vwery common

Soya Allergy is another common thing in recent times

My 5 yr old grandson was very ill from birth as a result of milk allergy so daughter had to avoid all dairy herself to breast feed him

He was then found to be allergic to Soya , eggs , passion fruit

He is now a very healthy 5 yr old with a football kick like the top players