Hello, Thank you for your inquiry. Cold sores are common to appear outside if the mouth and would be my possible diagnosis with your descritption. Typically they are contagious and of viral origin. This may last 7-10 days with no cure. Topical drugs such Abreva may shorten the length of symptoms and help limit pain. Presription anti-viral medications such acyclovir and famciclovir work best when taken during the first two days of the symptoms appearing. Avoid acidic and spicy foods. Cold packs and gels with benzocaine or other numbing ingredients may offer relief. Benadryl is a good antihistamine to reduce swelling and calm symptoms of spreading inflammation. I hope my suggests help your daughter to feel better soon. I am glad to answer additional questions and hope my comments are helpful.