Seriously, even though it sounds like I'm saying, "You're medically stupid." Too which I am.
I am also saying there are several illnesses that are combined with making people feel daft or stupid.
Hypcondria, brain cancer, allergies, inactive adrenal gland and so-on. The fact is you could simply try taking multi-vitamins, drink water and workout to feel better and maybe you will get better or go see a doctor who will give you exactly what you need and then drink water and exercise.