Lately I've been having a lot of trouble paying attention to people.  It's not that I drift off in the middle of what they're saying, it's that they never catch my attention in the first place.  Maybe I'll hear one or two words, but it takes a while to sink in that I should listen to them, if it sinks in at all.  Other times, I don't hear a single word and get in trouble later when I don't do what's expected of me- but I don't remember anything because I never heard a word.
What's really frustrating about this for my parents is that I (appearantly- I have no idea myself) give every impression of hearing and understanding them.  My mom says the only other time in my life that it was this bad, I was even capable of repeating word for word what she'd said without actually absorbing any of it or remembering that she'd even spoken to me at all.
This is now happening two or three times a day, resulting in all kinds of yelling and anger from my parents.  They say it's my problem and I have to figure out how to fix it, and until I do they're just going to keep punishing me, but I have no idea what's going on, let alone how to stop it.

Has anyone else experienced something like this?