Dropping like flies

We have gone from one coughing kid to anither one having an asthma attack and a persistent cough which then turned into  a nasty sinus infection to the last healthy one up at night coughing and another kid with a possible sinus infection. It sounds like an orchestra of coughing and snoring around here. The only bonus is the early to bed for all of them and they don't fight us on it. I have a feeling it's going to be a long nasty allergy season.