A. Those could definitely be a sign of a milk allergy or just a simple formula intolerance. Either way, it likely would be a good idea to not give him a milk based formula any longer.
Since some infants that have a problem with milk based formulas, like Enfamil Lipil, Similac Advance, or Good Start Supreme, can also have a problem with soy based formulas, one good option may be to just breastfeed more and not supplement with formula at all. Or you could try to pump and then supplement with your pumped breastmilk. If your main problem is your supply of breastmilk, a lactation consultant should be able to help you build up your supply so that you don't have to supplement as much. Breastfeeding or pumping more and an herb, like fenugreek, can also be helpful to build a mother's supply of breastmilk. See our guide to increasing your breastmilk supply for more information.
If stopping the supplements is not an option for you right now, than a soy formula should be another good thing to try. Many Pediatricians recommend changing to a soy formula to treat infants who are constipated. Other common treatments can include offering some extra water or diluted apple or prune juice once or twice a day.
An elemental formula, like Nutramigen or Alimentum, may be necessary if he also has a problem with soy. Or again, you might try to breastfeed more and not supplement at all in this case.
