Ok - so going off what you said - it could just be what we used to refer to as "burn out" when I was in school. Basically too much stress and studying/cramming for exams too much n too often causing your brain to go into overload for a bit and demand a bit of "rest and relaxation" ... or it could be depression. I would suggest going to a psychiatrist for a psychological eval just to check. In the meantime - try to increase your sleep. Simply schedule the hours of sleep and stick to them. If you cannot sleep - try putting a few drops of 100% therapeutic grade lavender essential oil on your pillow. You can also use essential oils to improve concentration but its best to see if simple rest helps first.
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