My 5yr old gets rash/hives on face and behind her ears after eating ice cream or water ice for a total of 4 incidences. why is this happening?

Cold urticaria?: Cold Urticaria (essentially meaning "cold hives") is an allergy where hives (urticaria) allergic rashes form on the skin after exposure to a cold stimulus. If this continues, have her see an allergist. best wishes.

Cholenergic hives: Your child may have cholenergic urticaria where his hives are being caused by exposure to cold

Rash: Perhaps child has developed a food sensitivity. Best, if you can, avoid foods you suspect. Then "test" to try to figure out which food it is. Ask your doctor about using a liquid antihistamine for the rash; ask about using benadryl (diphenhydramine) cream to apply to the rash. Problem is that, for example, milk may not be a problem normally. But milk plus fresh fruit may add up to enough allergy to cause symptoms.

Cold urticaria?: Assuming that water ice is water only, your son may have cold-induced urticaria, hives caused by exposure to cold. If this is the case, it is a "physical urticaria", caused by the cold. To find out exactly what goes on see a board-certified allergist/immunologist.

See a dermatologist: Loratadine is not likely to help this. Probably the child smears the cold treat on her face, and maybe you rub it off with a cloth or paper. She may have eczema. Localized conditions such as this are not food allergy. Possibly it is local irritation.