There could be multiple reasons for the problem that you have described. A proper clinical examination by a dentist would be the most appropriate steps at this point for a rational diagnosis. The least you can do is increase your water intake, clean your tongue regularly using your toothbrush and maintain good oral hygiene otherwise. Some bacterial and viral infectious states of the mouth can also be the reasons for the symptoms. But their treatment can be instituted only after the diagnosis has been confirmed. Regards.