We are not medical doctors here. However, because these episodes have gone on so long, I would recommend that you see a health care practitioner. Sometimes lightheadedness and dizziness are related to minor inner ear imbalances that aren't really serious, like labyrinthitis. OTC Dramamine or Bonine can help symptoms like these.
Your symptoms could also be related to diet or due to timing of exercise; there's just no way to know without a physical check-up, however, and having a doc take a look at you.
If you get your episodes at certain times of the day, it can be helpful to keep meclizine on hand (that's OTC Dramamine or Bonine). But I would still recommend that you see a doctor, if possible. Good luck.
Your electrolytes, vitamins, minerals could be off balance with is part of a healty lifestyle. Yes try to eat better and drink plenty of water