Ds (15) trains at least 2 hours a day for his sport, he is exceptionally good at it and wants to take it as far as he can. However his training keeps getting derailed by illness. So far this year he's had a chest infection which kept him off training for two weeks, the week before last he came down with a really heavy cold when he was streaming with snot (lovely!) and had red blotches all over his face, now he's come home with conjunctivitis. His coach called me to say he wanted ds to rest for at least 3 weeks - he's pulled him out of a big competition this week - and to get his general health checked out by a doctor.
He eats very healthily (for a 15 year old boy), doesn't get enough sleep (but that's another argument) and is obviously very fit. Is there anything I can do to boost his immune system and is there anything a doctor could suggest?