Raven, bless your HEART!! I'm always talking about Prednisone making me depressed -- even suicidal -- but, I had a breast biopsy 20+ years ago (benign) and came out of THAT very depressed, too. I did reasearch, and like 4-eyes said, post-surgery depression is VERY, VERY common. Some people have this reaction due to the anesthesia -- some to the IVs -- some to the drugs used afterwards -- and some due to the trauma. I'd say you might have a "touch" of all of these.
It can take SIX MONTHS or longer for the anesthesia to completely LEAVE your system. I visited my allergist -- who called another doctor (at Emory, I think) -- who said that it might help to eat -- get this.............FRIED foods (meats included)..........and drink a lot of water and tea. Apparently, the drugs "bind" to the oil/grease and the liquids flush them out of the body (or something like this) -- or the fried foods change the ph of the body (I really can't remember for sure). WHATEVER it was -- in a couple of days of eating burgers and fries (I still ate beef back then), I was feeling MUCH better. So, hang in there -- others HAVE been through this -- you are NOT alone -- it will get better -- just be kind to yourself.
I'd say to JUST go and get an anti-depressant -- but, it can take SIX weeks for them to kick-in. Of course, you might want to get an anti-depressant AND eat McDonalds, too!
BIG