Visit a dental office, as proper investigations and physical condition of tongue is yet to be seen. Halitosis has several causes which involves poor oral oral hygiene, food lodgement, constipation, dry mouth etc.
Next Steps
first you should get your teeth checked than dentist can consider about probable cause of halitosis n white patchy tongue.
Health Tips
you should try to clean your tongue with a tongue cleaner, drink ample water, use mouth wash rinse.