I think it is quite common to have depression upon giving up a dependancy on alcohol and pills. They actually cause depression and it takes some time to pull out of it and for our bodies and minds to heal.
I think many of us may have depression anyway, and used the alcohol and drugs to self-medicate.
Hang in there and see what more sober time brings. I feel much better when I make time to exercise, even if I have to force myself.