A gradual (from age 13 to age 15, or so) and slight loss of "eloquence," or one's ability to effectively and elegantly phrase his thoughts.

A slight feeling of mental "slowness" gradually increasing through the same period.

A slight increase, over those years, in general "clumsiness," especially in "sloppy" speech.

A slight (at least perceived) slowing in mental development as compared to the youth in question's peers and prior development.

Am I (15, male) merely a hypochondriac, or are these symptoms a harbinger of a serious neurological disorder? Thank you in advance.