Kitt's right. Hit the depression forum and no, there's no particular age that depression can begin. I've read that panic attacks usually begin in a person's mid-20's. That's what happened to me. But depression can hit anyone at anytime.
Depression is not a life sentence. It can be kicked to the curb. Get a therapist and make sure you see him/her regularly. I hope you are back to "normal" soon!!
Generalized Anxiety Disorder
60 mg. Prozac, Ativan as needed.
"Nothing makes us so lonely as our secrets." Paul Tournier