Thanks for posting your query.Bad breath
or halitosis is caused to many reasons. It can range from simple things like not drinking enough water to having Gastrointestinal problems. Having bad oral hygiene
like having tartar which leads to many gum diseases like periodontitis
or having decayed tooth also causes bad breath. Systemic disease like diabetes also causes bad breath. You need to see a dentist
who will asses your condition and advise treatment accordingly.
Discolouration of teeth are of two types, intrinsic[ inside] or extrinsic [outside]. Intrinsic stains such as tetracycline
or fluoride are not related to bad breath .In order to correct these you can undergo bleaching or whitening of your teeth. Specialised treatment procedures like laminates or crowns may help in masking tough stains.
Extrinsic stains are those caused due to tartar, pan chewing, cavities, etc. which can be related to bad breath. You will need to undergo scaling or treatment of the cavities according to the cause of the problem.
Hope that answers your query.