Here is the thread where I blogged about Bella during her luxating patella surgery recovery (one knee):
http://www.yorkietalk.com/forums/sic...a-surgery.html . You might want to check it out, because it also has advice from very experienced Yorkietalkers, as well as others whose Yorkies had LP surgery and were going through recovery at the same time Bella was.
It looks like we used metacam as a pain killer for about two weeks, and then she was fine after that. She recovered very quickly because she was only one year old when we had her surgery done. Our biggest problems were (1) getting her to drink water (we ended up making home-made chicken broth) and (2) keeping her from being *too* active (climbing stairs, jumping, etc.).
I reviewed this thread, and it looks like Max had his surgery on April 11, which is 2 1/2 weeks or so ago. I would definitely tell the vet about the yelps of pain, just to be sure that nothing is going wrong. I'm sure that your physical therapist is also well-trained to detect issues during recovery. Best wishes for a speedy recovery, and keep us posted on Max's progress! The information you are providing will be very helpful for people with Yorkies going through double LP surgery in the future.