Could it be and over-active imagination/brain? I can't concentrate on just one thing most of the time because my brain just isn't being stimulated enough. I have a very hard time reading books and am now even having trouble playing video games unless they move very fast or require a lot of thinking...and if I'm watching TV or doing something else at the same time too. I also worry that I've missed things and (I don't know if it's directly related) I watch the same TV shows to the point that I can almost say the next line sometimes.