M.P.
If it's at all possible, I would ask to be referred to an allergist. I think the Alimentum still has some milk and soy in the formula (even though it's broken down). There are other formulas that an allergist can recommend, and your insurance may even cover it if the doctor writes a prescription for it. But it's important to find out if there is an allergy at play either to milk or soy or both, and the severity of it. If there is, an allergist can put you on the right path to avoid that allergen.
Take care and good luck with the doctor...