Most halitosis result from dental caries or periodontal disease. Seeing a dentist is advised.
Halitosis if more often a result of acid reflux or GERD. Not only rule out cavities and perio disease but see your PCM for a review of reflux or gerd. Often it could be a combination of this but more often it's coming from your stomach and not the actual mouth!!! Good luck!
I am also having the same problem for almost 15 years. The problem is serious and needs an early cure. The more time you take, more difficult the problem is. You should visit a dentist first and check your oral health. Plaque severely cause bad breath and just dental cleaning may greatly reduce your halitosis problem. If the problem persist, do visit an ENT specialist. Many times, bad breath is due to acid reflux ( just like i am having) which is a more serious condition of breath as mouthwash can not hide the smell. The best treatment is in your hand. keep your mouth clean. Daily brush twice and floss. keep the tongue clean as bacteria are present inside the upper layer of tongue. Try to drink as much water as you can (5 to 7 litres a day). Avoid drinking alcohol, smoking, tea, Coffey and cold drinks. try to minimize the use of onion, garlic, dairy products from your daily diet.
See friend, you are not responsible for the bad breath but the silly bacteria is causing the smell. So forget the past, go to a dentist, ENT. Tell your problem to doctor with all details and also discuss the problem with your parents so that your mind will be very much relaxed. If you are using any mouthwash, don't use the mouthwash having alcoholic percentage because the alcohol reduces the saliva in your mouth and dry mouth is more susceptible to bad breath.
So, drink plenty water and keep your breath fresh.