You can lick the back of your hand and smell it. if it smells bad even after brushing in the morning you might have a problem. i remember reading an article about a girl stating she had a problem with bad breath even though she brushed her teeth twice and used mouthwash regularly. There after she booked an appointment with her dentist and there was indeed a problem(idk if it was her teeth, tounge or throught) and the dentist prescribed her with some tablets, that u have to let sit on ur tounge and dissolve and the problem was solved. But the chances are u might just be paranoid. however if u still feel like theres something wrong i really recommend seeing a dentist and telling them about ur issue.