I would say certain things sound like a typical teen. Putting clothes in a basket and not folding them, for example, is just a kid being a kid. Not remembering taking them out of the basket is odd. I have some memory loss and confusion with things like that. I forget to do things all the time. I forget if I've done things, too. Even if I have lists to follow or little reminder notes, I still forget. The only way to remember some things is to have a flashing blinking something following me around. I don't know if this is my bipolar or not.
You should take him in to the doctor and describe these things. He will probably need some tests done both pysical and mental. I hope you can find an answer.
And also it would be better if you spoke to a doctor about it if he is being sincere about his memory loss and not exaggerating it or what not after thinking it over and telling them since we can't do diagnosing here and please give us a follow up.
Could be anything from a tumor as I read memory loss like that happened before for someone to a form of amnesia and there's also some mental illnesses that can cause something like this but they have to have several other diagnostic criteria points to be diagnosed. Think really hard about it if there are other things not right with your son.