Yes you can give Ziretc (cetzine) immediately after Calpol
You have not mentioned about fever
. If there is no fever, only itch- it might be some form of allergy
. Zirtec will help. Caladryl
lotion which has an antihistamine in it will also help.
But if she has fever too, it might be some virus. You may give Calpol every 6hours.
Please do visit your doctor and get things confirmed.
Please bear in mind that allergic reactions can be life threatening too. If at any time she develops itching in the tongue, lips etc, breathing difficulty etc- please do not hesitate to take her to ER.
Hope my answer helps you.
Wish your daughter good health.