Can only offer you perspective through the lens of my own experiences (Diagnosed Bipolar/ADHD) - School was a terrible experience for me, and it started around 5th/6th Grade - Not for lack of intelligence by any means - I knew I was smart - I was convinced I was smarter than my teachers and I didn't need them... and if I struggled in an area it wasn't for lack of effort - it was for lack of interest. Of course when I was a kid, medications for ADD/ADHD were just in their infancy, so I went without - and as a result, never made it through HS (Got my GED at 17 like it wasn't even a problem, didn't even study prior to taking it) Not sure how much I can blame not having Ritalin for that - there was a SLEW of other issues going on at that time which only further exacerbated the problem... Video Games and books became my escape from my from my overbearing but emotionally stunted parents, my mediocre teachers, and my vapid classmates. And if those things weren't available - I had just enough access to get my hands on whatever drugs I wanted - Parent's be damned. What did they know anyway? Am I scaring you yet?

Chances are, your kid is smart - likely too smart for his own good, and he feels stuck in a world of mediocrity. You (and the school) need to figure out ways to challenge him intellectually - Find an interest that resonates with him, and he'll likely become an expert in it within a fairly short time span - consider enrolling him in a program for the gifted and talented.