My three year old have canker sores in lip and inside mouth and fever she oftenly have canter sores in her mouth i take her to the hospital pediatric says thus is common in children i m very worried about her no canker sores in her feet and hands?

Multiple sores with fever probably are not canker sores. "No sores in her feet and hands" suggests you may be familiar with hand foot and mouth disease, which still might be possible. More important, oral herpes is possible, especially if she has contact with other toddlers (e.g. day care). Herpes is important because there is effective treatment. Discuss with the pediatrician ASAP. Good luck.

A cold sore can lead to fever in a child. A canker sore can be from drinking too much acidic juices. Cut back on sugary beverages. See a dentist if these symptoms continue.