I personally don't know you so I can only give you a spectators outlook.
One of your dogs just had a really awful experience, and I think you should wait a little while to let it all ride through before you consider another dog. Financially if you can swing it, then you can swing it if you wait a little while. I don't know if a puppy jumping around Mack's newly healing surgery incisions would be the wisest choice. I know he's getting the stitches out soon, but he still needs some quiet time. He may look great but it's only been a week? or two weeks? I wouldn't think it would be the best time to add to the household.
Puppy fever is a tough thing to battle, looking at those little faces makes it a challenge, but personally I would just hold out a few months before you can have everything settled again.
As for the the breeder situation, I think it's anyone's personal decision to make. Yes, everyone can weigh in and advise in any way they want but ultimately it's them who choses what they do and how they decide to take it. So for me, I trust that someone with experience from this breeder would have good judgement. One more thing, Shih Tzu not s**tzu hehehehe
