Before considering surgery to clear your nasal
passages, you should ask the ENT if a nasal
steroid spray might open your nasal
passages. If a trial of that doesn't help, you should ask him/her if the deviated nasal septum is causing enough blockage that straightening it would give you a lot of relief.
The relationship of dizziness and lightheadedness to eating suggests that you might be having bouts of hypoglycemia. This can sometimes be the first sign of diabetes.