What milk do you give him now? My ds1 has a CMP allergy. He was on special formula until he was 3yrs old. Then he went into rice milk. We tried oat, and almond milk but rice milk was all he'd take. The GP and his paeds were happy
Stick with the formula - assuming you are using a specialist one that is dairy free. The replacement milks are not so good nutritionally and also carry their own risks (e.g. arsenic in rice milk, phyto-oestrogens in soya milk).