to YT!!!
I am not certain...and I hope there are others on here who may be of help to you.
It may well be something from the breeders home or what they used for washing.....I recall when I bought my first small dog (a Shih-tzu many years ago), I would itch all the time playing w/ him that first day. I took him to the vet and groomer.....after a good grooming....it was better...and after a while (a few days or so), and washing him at home, everything was fine.
So....I would try washing her with a good dog shampoo (I like Buddy Wash and PetSilk and SheaPet) or take her to a groomer for a good bath.
My mother is allergic to animals.....even when she comes over to our house, her eyes will get watery, etc. I don't know if it is our labs or our yorkies??? It is something that she can stand...and not severe....but I just hate it that she does it.
You may want to check out the grooming section here also...might be some good tips there too that may be helpful.
And if all else....you can ask the vet or your doctor too.