Interesting about the blood groups as I had no idea at all there might be a link. AB- is the group of for the milk protein intolerant family members. DS's family is Romanian so not a traditionally dairy free nationality like the Japanese.
If he likes beige and bland foods then almonds may be your friend for extra calcium so long as he likes the flavour. Our quick brekky is usually a nut/seed butter on toast.
Tinned sardines with the bones in are a great "fast food" for the dairy intolerant when you are feeling lazy. (DS loves sardine and spinach sarnies) McDonald's is often safer to eat out at than the gourmet organic cafe type places
. Wetherspoons is NOT your friend now - it's the worst high st gaff I've come across for the dairy free, just avoid.
Avocados when in season are a great source of the right type of fats, and very versatile. Somewhere I have a recipe for chocolate mousse using avocado. The fat content of the diet is extra important for our kids meethinks as the brain is 90% fat. Also dairy contains an awful lot of fat soluble vitamins so I think seeing a clinical dietician is a brilliant idea to ensure your child still gets enough of these when you go dairy free.
I crack an egg over homemade pizza having never found a dairy-free cheese alternative that didn't taste like S%&*t. We have a homemade pizza and popcorn night once a week and that's how I got DS to try diff veggies (as toppings). Once he's had them on a pizza he'll accept them as part of other meals. Worth trying for a fussy eater as kids love making their own pizzas - it's a trick that several of my friends have nicked off me now.
You'll take a few months to read packets and get comfy with brands (often the basics range of biscuits etc is most likely to be dairy free). Then all's well until some ijeet decides to "improve" a recipe!
Often the basics range in supermarkets has the least amount of e numbers/stuff you can't pronounce & is most likely to be dairy free, for naughty items like biscuits.
I do a lot of scratch cooking - not cos I'm a domestic goddess type but cos I just don't have the patience to squint at all the ready meal labels. This means by default DS actually has a diet with less additives than many of his friends lol!
I'll try and type up some "lazy-arsed mam" muffin recipes for you next week.
If he has school dinners - watch out! Schools vary a helluva lot in how they interpret this in terms of providing a full balanced meal & if your school cook isn't a great one, then a kid ends up just going hungry. Make sure you check for a few weeks what the child is actually getting as DS came home crying with hunger when we tried it at one school. Other schools are fab.