go get it checked out. Take bunch of fiber.
Bad diet. Plain and simple.
If you eat crap food your stool goes hard and is hard to digest, once you switch to a healthy diet, guess what, the stool goes normal again. It's all the crap they put in food nowadays, additives, preservatives, chemicals.
Switch to more fruit and fresh veg and also get some fibre in the diet it will clear up and the digestion will go back to normal.
They need to improve their diet, exercise habits and oral hygiene. If you get the 25-30gm of fibre a day that is recommended, these problems will ease. However, if they are not used to fibre, it needs to be introduced by stepping up the amount of fibre a bit at a time. Fruits, veg, nuts, beans, are all important and tasty sources of fibre. And now high fibre pasta is available. It looks and tastes just like white pasta, but has about a third of your days requirement of fibre. The exercise will help with the bowel movements (a 30 min brisk walk will do wonders), as well as easing the gas. And as for the bad breath, brush well, don't forget to brush your tongue too, and floss. Make sure to drink plenty of water. Cigs and coffee are notorious for causing bad breath.
These symptoms don't sound serious alone, but may be indicators of something else. Please see your doctor.
and, I know I'm not getting best answer for this little chewing out session, but here goes: most people on yahoo answers are not professionals! If you have suffered this for so very long you need to see a doctor, pronto, and not ask advice from people who may not know what they are talking about. scuse please while I rant off--chew gum, better oral hygiene? please! this is the kind of stuff you will get here, because the general populace doesn't know any better! Please, see a doctor immediately. It may be your gallbladder as the other gentleman mentioned, or it may be something else. It may even be something curable with a proper diet, which I am sure you have already tried if you have this going on for so long, but you will not know until you see a doctor and get a good checkup done. You will not be able to read the autopsy report if it comes to that, so please see your doctor.
When you get constipated your belly can become distended (enlarged), meaning you can get impacted(backed up). Certain medications can cause constipation, like pain pills, if your on narcotics you could get some laxatives, or suppositories and try to keep your self regular.Drink lots of water it helps with constipation. If caused by something else, I can't think of an example of what else it could be, I guess that means a doctor. I would think the bad breath is a separate problem, could be caused by dental problems, certain other conditions can cause this also. The safe and smartest thing to do is to see a doctor. good luck