Till What Age Can Neogain Be Given To Infant?

hi doctor, my son is 4 and half month old,he he getting loose motions very month and after somany tests we came to know that he is alergitic to soya protien and now we are feeding him neogain as adviced by doctor,til how many months we can feed him this powder as he is not havingmother milk and can we start giving him nestum from now onwords for