Mom of 1 - one additional thought (and thanks for asking the question; I've benefitted from the responses as well) - have you tried playing with the antihistamine you use? I found my boys responded to different antihistamines quite differently, and if we changed, it affected asthma control. We also -with the advice of our doctor and pharmacist - upped the dosage beyond the normally prescribed dose temporarily during the worst of allergy season.
Oh, and beyond all of the things I'm sure you're already doing to fight the allergies, we found that if my son showered and washed the pollen out of his hair before bed and if we changed his pillowcase nightly, it really helped.
