Can you safely record a video clip of them wheezing?
Can you keep a diary of how often they had symptoms?
Does it only happen when they have a cold, or can they have symptoms in between?
Look for the trigger factors such as dust, animal fur, pollen, or when your child gets excited. What factors have triggered off symptoms in your child?
What type of medicines have they received to treat it and which did you think worked?
Does asthma, hayfever or eczema run in the family?