asthmatic 3 1/2 year old

Hi there

I am looking for advice if possible. my 3 1/2 year old diagnosed asthmatic 2 years ago, is on montelukast, serotide and ventolin, has had tonsils and adenoids removed due to constant infections and apnea, has had every test going, sweat, blood, immunity, all negative. even had 12 week course of low dose antibiotics. He has approx 4 weeks symptom free then starts with a cough, usually constant, wet and productive whcih then results in him being unwell and onto antibiotics, clears up after 4-6 weeks. and this has been a constant cycle for 2 years but he never seems to improve. He is a good height and weight for his age, bright with a good diet. due to start full time school in september which he will struggle with if no improvement in his health as when he is ill, normality doesn't exist.

Mel