there are various causes for whitish patches over tongue..commonly occurs after an episode of systemic infection such as viral fever or typhoid fever. other conditions which can cause patches include candidiasis, leukoplakia. most often asymptotic white patches are benign and caller as geographic tongue and resolve spontaneously. for confirmation consult ENT specialist or oral surgeon

Sorry, I will need to see your mouth before I can comment. Drop into my clinic Healthcare@Basaveshwaranagar for a consult