Question about constant sadness/down-moodiness?

I was diagnosed with Dysthymia disorder (I don't know which type though) in a wilderness program (Three Rivers Montana) by Dr. John Platt, MD. This is weird, but I recently looked at my "file" (in a theutic boarding school, clified) and I saw that this was one there. Then when I asked the therapists about it, it got worst. It's weird because I thought being aware of "hidden" disorders was supposed to help the person, but it doesn't for me. It has actually gotten worse. I don't know what to do, I've talked to the therapists here and they said that it's usually situation based. Other thing's I've also read have said it has to do with what I put into/out of my body (eating and exercise). I exercise almost everyday, eat pretty healthily (if I don't I work it off), and I've been doing that for a few months now. I haven't seen any marginal improvement. My weaknesses? I almost never know what to think about, I see joy in material things for a limited time, I'm obsessed with leaving this school in April, and I over-yse things (this can help sometimes, but not always). I also have a very troubled past and I've put myself into a situation that can be ended as soon as I'm independent. I've done this before, but I'd love to be contacted on Y! Messenger so we can have a one on one, that'll make communication a lot easier. It'd mean a lot....thank you in advance and God Bless. P.S. I started feeling mild symptoms of this when I turned 15. I'm 17 now.