Experiencing a bitter tongue can be a side effect of taking the medication "Lansoprazole". A bitter tongue would probably cease when you stop taking Lansoprazole.
Bad breath can also be caused by several other reasons: throat infection, mouth infection, cavities, bad hygiene of the teeth and mouth, adigestive disorder⦠You can consult a dentist about the fetid odor. If the teeth and mouth are OK then you can consult some ENT-specialist and internist for more examinations.