Try changing enviroments inside of school? Like studyiing elswhere, trying to get into new social groups inside of school, etc?

I nearly dropped out of University because I had nearly one whole year when I just couldn't get myself to go to University. I study art and had a very bad teacher (at least she was bad for me, but countless other students told of similar feelings) and I felt like I couldn't do anything right. Like I couldn't draw at all.
Then I somehow managed to get into another teacher's class (I lost a whole year, though) and I started feeling better.
But drawing/painting is still very hard (and I'll graduate in a few months...) as I feel like I'm just not good enough and I don't have the will to continue...

But yeah, back to the original poster: Have you tried 'lining up' your successes? Putting them on the wall for example? (Tests with good grades, printed-out good online grades?) You musn't forget your successes and the fact that you are able to succeed.