Hi, I'm no expert, but your description of the spreading red bruise
reminded me of something that one of my ferrets had after adrenal surgery.
Chip had lost all his fur so we could really see it.  After surgery, the
skin from his abdomen to his leg took on a purplish red bruise.  It spread
fast and I was terrified!  But Chip was acting fine and the vet said not
to worry.  It spread and spread until one whole side was raspberry-colored.
Then it stopped.  A few days later it was gone.  Chip was fine.  Go figure!
But do check again with your vet.  Good luck,
 
Kat
[Posted in FML issue 2600]