Hey, John:
It is probably due to steroid withdrawals; they usually really hammer a person with prednisone after such a surgery. I had so much that it caused a diabetic issue, somewhat temporary but now borderline type II.
Just monitor Your blood sugar and if low, it could be hypoglycemia as the steroids mess with this as well as mood-modulating hormones; from depression to "'roid rage."
Just so You will know--it will not last because it is due to the drugs--try and have a bit of crack in meantime.
Cheerio,
John
