I'm afraid this is not something I have any experience with, so I do hope someone else will be able to give some advice.
As a general comment.......I do think you need a little time and a bit more information before you opt for more surgery, although in the end you will probably find it is best to take the specialist's advice.
I would suggest when when speaking to the Specialist you have a list of whatever you want to ask written down, and you write down what he tells you the latest scan has revealed.
If they want to operate , check out if the surgery is urgent. If your boy is being kept comfortable then it may be worth telling them that you would appreciate a little time to make a decision.
His last surgery is so recent, I think you need to be sure of all the facts in your own mind before you can feel right about agreeing to more.
Cavaliers......Tommy Tuppence 2000-2012 and a half share of Faith.
Japanese Chins.... Dandy, Benny, Bridgette and Hana.