Hi i brush my teeth for too long in the morning and night.. when i wake up in the morning my mouth is dry and my tongue will have a whitish coating. I will first brush my tongue to make sure it is perfectly clean but then id brush my teeth for half an hour.. not hard but i d brush every invidual tooth really slowly ..to make sure my teeth feel clean and then id use mouthwash.. but say give three hours after without eating i will get a bad taste in my mouth.. the same happens when i eat but my tongue wouls go a little yellow at the back... it is sort of a sour bad taste but not too sour.. then at night i do the same thing but floss. I dont understand why my tongue is going yellow and i am gettiyng a bad taste. Its being going on for at least a year.. but before there were no problems 100% fresh breath and constant clean tongue i didnt even need to clean my tongue at all then! i have been to a dentist and they say everyyhing is fine but i can see one tooth molar i think with loads of black seed like shapes indented ob them which i think are cavities... can anyone help me out ?