A rotten taste could be related to halitosis, also known as bad breath.
Bad breath is an unpleasant condition that can be cause for embarrassment. If you don't brush and floss daily, particles of food remain in the mouth, collecting bacteria, which can cause bad breath. Food that collects between the teeth, on the tongue and around the gums can rot, leaving an unpleasant odor. Some people with bad breath aren’t even aware there’s a problem. If you’re concerned about bad breath, see your dentist. He or she can help identify the cause and, if it’s due to an oral condition, develop a treatment plan to help eliminate it.