What maybe the cause of this white patches on my tongue?

Many causes: There are a number of things that can cause whilte patches on your tongue ranging from harmless geographic tongue to thrush, trauma, bite, infections, and several diseases. See you dentist if you do not remember biting your tongue recently.

Best to be seen: There are lots of things that can cause white patches on the tongue. Some are benign and require no treatment. Some require treatment and a few require a biopsy for a definitive diagnosis as they can be potentially dangerous and even if they look harmless may not be! all white patches lasting more than 2 weeks mandate you seeing a dentist for a diagnosis. Always best not to take chances.