Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your health concerns... As per your complain if you have all your teeth decayed then it is very much apparent that there must be infection in many of your teeth as well as gums and the bad breath is also due to multiple decayed teeth which would also be causing food lodgements and poor hygiene conditions in your mouth and all of this must be having deleterious effect on the gums causing gum infection also.. You are feeling sick in your stomach as well as there is weakness because of two reasons: 1.The bacteria present in the mouth that is causing infections must be getting carried to the stomach along with food and water and causing stomach infections leading to stomach upset, indigestion, improper absorption of nutrients into the body leading to weakness as well.. 2.In absence of healthy teeth the food is not being chewed well and as some of the digestive process starts in the mouth itself with the enzymes present in the saliva, so when food is not chewed well this process is also disturbed and when the unchewed or partially chewed food reaches the stomach the digestion is more or less incomplete and it can add up to indigestion. The best way to get rid of all this is that you should get the treatment of your teeth done by a dentist.Get a full mouth x-ray known as ORTHOPANTOMOGRAM [OPG] done and get all your teeth evaluated.. In case for those teeth which could not be saved,get them extracted while those teeth which have some scope of preserving its better to get them treated with root canal treatment followed by capping of teeth with or without post and core as per the requirement.. The teeth extracted can be replaced with either removable or fixed dental prosthesis.. Brush your teeth twice daily and use concentrated mouthwash twice a day for gargles and reducing bacterial count.. Do warm saline gargles twice a day.. Always gargle with water or using mouthwash after meals.. For stomach infection you can consult a Gastroenterologist to get ruled out whether you have infection or not.. In case of stomach infection Ciprofloxacin 5OO mg twice a day, Metronidazole 4OO mg three times a day and Pantoprazole 4O mg once in morning empty stomach and once at night.. Drink plenty of water and take nutritious diet.. Hope this information helps.. If you find the answer helpful please give me a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora..