Does it taste sour? Is it gushing when opened? If it is, it is probably a gusher infection.
Or, is it just plain bad tasting, due to the recipe? If you post your recipe, maybe we can figure out what went wrong. In addition, could you describe the bad flavor? Like, astringent, salty, soapy, bitter, sour (sour like sour milk, or sour like vinegar- different kinds of sour even), etc.