"energy drinks" have you read the labels on any of the ones your drink. 90% of them are sugar and caffeine alone. So you will crash from drinking those even if you did not "overuse" them.
You can start by making a schedule on paper. List a 24hour day and Sun-Sat and fill it in with your schedule. Go back over it and see how little sleep your giving your body. 8 hrs a day at least is prefered. Then look into your diet what are you eating, is it mostly junk, or is it healthy...the old saying you are what you eat is VERY true.
After a few corrections, I think you may find a boost in energy and money form the lack of "drinks". Not to mention the lack of crashing you will be doing. If you still are feeling tired, then I would brring it up to your doctor, personally.