for yellow teeth you need to get a professional cleaning done. If that does not help then you may go for teeth whitening
. There are various reasons of bad breath
, like impurities in blood, inefficient digestive system, dry mouth
(lack of saliva production), gum disease, cavities
, plaque and tartar formation around teeth and gums, kind of diet
, improper brushing / cleaning of mouth etc. I would advise you to get a thorough physical and dental examination to rule out the cause of bad breath and to solve it permanently.