I want to be really careful giving advice about a possible allergy, but some kids do just get contact dermatitis from cinnamon initially w/out being allergic. DS got a red rash everywhere that it touched his face one of the first times I gave it to him, but he eats it now without a problem. I knew when he got the rash that he had cinnamon in things before (like baked goods) without any issue. Good luck and just be super careful.
Re: XP: Ugh... cinnamon allergy