The least dramatic, but most likely, reason for your torpor is vitamin deficiency, particularly the B vitamins. Get yourself some heavy duty supplements to start with. One you begin to recover, reduce to maintainance doses.
And improve you diet. Make sure you get enough meat, vegetables, fruit, and fats. Yes, we need fats. Surprise, surprise! Cut out the junk and sugars.
These sound like common signs of add and maybe some depression you should get a full mental health examine by a psychiatrist they can give you a proper dx and find the best treatment for you.How you go about this is different if you have a primary care Dr they can give you some names of a physiatrist in you area if you have insurance you can call the insurance company and the can give you a list of psychiatrist. If not then i do know if your school a a medical center if the do the can also help.So bottom line is you should see a Dr and get a dx and then go from there.