Did you introduce anything new into his diet? Any new meds? Is he sick at all? If not, then it may be that he started out okay on the Ali but over time the partially broken down milk proteins have built up in his system and he is starting to react to them. If that’s the case, then your GI prob will want you on an elemental formula. They are completely hypoallergenic and made up of individual amino acids (the building blocks of protein) which are easier for babies with allergies to digest. I would hold off on starting solids until things get back to normal, and then just be sure to avoid anything with milk and soy. You might also want to start out with introducing just one new food at a time, so if he does have a reaction you will know exactly what caused it. Good luck!