What can I give my 6 month & 3 yr old for their allergies? Please Help!!!!?

Yes I have called the doctors, I have been trying all morning and when I finally got thru she put me to a nurse who didnt answer and hasnt returned my call and its been a couple hrs..! Both of them have a stuffy/runny nose, sneezing, and a congested cough and I figure its just allergies or sinuses cause thats what everyone else has and I have been using the "little noses" saline solution and a nose bulb to suck the mucus out but they are still having trouble breathing is there anything SAFE that I can give them? someone told me zyrtec but I dont know how much to give .. any help???