Yes, I did the blood test for Omi and she is basically allergic to both common grasses in our area as well as trees. Dust too!!
Benedryl doesnt work other than knocking her out. But I was given a shampoo from the vet (forget what kind, I'm at work) and was told to bathe her at least once a week and was also given a leave in conditioner that contains a bit of cortisone cream. Can I tell you - its AWESOME. As long as I keep up on the baths - she is just fine.
It also helps to wipe them down after each walk. I keep baby wipes by my door during Omi Allergy Season LOL