What kind of operation was it? Some medical problems, especially with the heart, can cause depression all of their own and that might have had something to do with everything going to heck in a hand basket?

http://my.clevelandclinic.org/heart/...nandheart.aspx

And, the blunted affect could be a result of medical problems as well:

http://brn.sagepub.com/content/13/2/164.abstract