Hi dear , The symptoms you mention in query can occur due to many reasons but the most common reason for this is poor oral hygiene . The bacteria can grow between the papillae, giving the tongue a black appearance. Other reasons are changes in the normal levels of yeast or bacteria in the mouth can occur after the use of certain antibiotics , mouth breathing , products containing bismuth and Sjogren’s syndrome . I would suggest you to maintain proper oral hygiene by brushing , flossing and scraping your tongue twice a day . Also avoid smoking . If condition doesn t get better in a week then consult oral pathologist for proper diagnosis and treatment . Hope your concern has been resolved. get well soon. Best Wishes, Dr. Harry Maheshwari