Back to eating with everyone else, not just little bits here and there. He has been very despondent even though he is doing brilliantly (and he has been so lucky). Going to get him checked out by the doctor in the week just to make sure he's ok (and he didn't even moan when I suggested it, must be feeling poorly).
Thanks all, taking him to his own (very recently acquired) GP. Didn't really get much in the way of 'care instructions' from QE but he will have to have another scan at QE in a couple of months.