You are not alone!!! I agree with all the above posts. I would also like to add that I personally had depression, and it was worse before surgery and I took medication after surgery also.
I started walking the day of my surgery in the hospital at the nurses advice, and I have continued to exercise almost daily since.
I weight lift, do bodycombat (an aerobic martial arts-kind of like Tae-Bo) and I walk and run. It not only transformed my body but also my mind.
I am no longer on any meds and I feel great. I am not saying that this is the only thing that may help you and of course, meds are so often needed, but even if you choose medication-try uping your exercising too and create those wonderful, natural endorphins....it really worked for me and I never thought I would be an avid exerciser, ever!
I wish you all the best and this was just my 2 cents, you hang in there and feel better soon!