maybe your burnt out?
been dieting/training hard aswell?
My concentration is blown, some of its the EC but not really because I should easily beable to focus with some caffiene. Its more I can't keep the gym and girls off my mind.
Its probably just you've lost focus on the importance of whatever it is you need to be memorizing. Thats whats happened to me, I should have easily passed my CCIE prequal exam, but i just couldn't fucking study. Losing the drive to really concentrate on what I'm learning.
Is it just everyday things? stressed out? If its studying for something try to focus on why you want to learn what your studying and how its going to take you places when you succeed. If its just ED things like dates, numbers ect.. you can't recall. Look into the burnt out aspect of you life, destress, eat a lil more. make sure your not lacking in any nutrition, heavy gym + dieting almost always makes you lack in that department.