What's wrong with me?

Be more specific.
Do you have any learning disabilities? It could be depression, too...

First guess would be a B vitamin deficiency. There ar 13 or 17 B vitamins, depending on who does the counting, and deficiencies are mostly psychological. Pills are cheap so keep some near you and take them when you notice you need them. Vitamin B2 makes your pee bright yellow, so when the color thins it's time for another pill.