My One Year Old Granddaughter Is Experiencing Eyes Rolling Back

My one year old granddaughter is experiencing eyes rolling back for a few seconds. She is very bright and alert, an early talker, but just starting to walk. Her parents note it happens most when she is tired or eating. However, now they have begun to notice it when she is crawling. It began after a virus with a fever. She has been congested several times since…never any antibiotics. Could an ear problem cause this? If not, what else?