Dylan barged back in through the cat door and started his hissing again!! We have him back out now.....Dennis is working on the little door now so he can't do it again. Thanks all. I believe everyone is exactly right about the hissing - I just want the house back to normal - I guess this surgery and the smells really has everyone rattled - including Meowmie I have a few pictures to make another thread and will do that.
Thank you to everyone who responded to me here!! I am SOOO thankful for PT!!