How can i cure my 4yrs old daughters cold?

I have twin daughters of 4yrs age.they always suffer from cold, one of them's breathing is noisy, sounds like wheezing sometimes.i give them ayurvedic medicines for cold, but i'm giving them almost all days and still the cold is not going fully.sometimes the cold comes down, but the day they go to nursery everything comes back.They love ice-cream, but how will i give them,when their cold never vanishes..