2yr old is mildly sunburned?

I have had the same thing today too despite applying suncream and he is not at all badly burnt but after his bath showed up more flush than normal over his cheeks and nose- he's extremely fair but so far I've always managed to screen him ok. I've just applied aftersun and made sure he was hydrated and his room is cool (has a fan). I've checked on him and he's fast asleep contentedly. I would adminsiter calpol if he complained or seemed uncomfortable but what you have done seems entirely sensible and to keep skin moisturised and him hydrated is the important things. Check on him regularly. I guess both of us will be much more proactive tomorrow!