H.
I would almost bet that it is allergies, as the other moms suggested. You are in a completely different part of the country now with a completely different set of allergens. My 3 year old developed a cough about 2 months ago that was worse at night. It was so bad that she would gag herself at times. I suspected allergies since she was otherwise completely normal, no fever or nasal discharge. We started Zyrtec as well. I ended up having to dose her twice a day instead of once a day early on, but she is now cough free. We now have her back to once a day dosing. I don't know how long you have been giving the Zyrtec, but it can take a week or two to work. So hang in there! Also, I read in one response about giving Sudafed. That is no longer approved or recommended for young children due to side effects, so please don't give him that.