Hi. My 12 year old girl suffer from eczema since she was born. From time to time she has sporadic episodes of allergy and her skin gets hives that get clear in a short period of time. However, the last two weeks she has had twice hives. Last night, after getting several mosquitos bites, she got the hives all over her body and today she is still having a few ones. I gave her Benadryl at 6:pm and she is better, but not 100% clear. Can I give her Cyproheptadine prescribed by her doctor? A lso, she has pain in her left knee. Is that pain related to the allergy?