I found that my Teddy Bear recovered quickly from liver shunt surgery. I don't think he was on pain meds after a few days. He had liver shunt and bladder stone surgery at the same time.
Not sure what that twitching is, but I would not assume it is pain. Is she panting when she is awake? Is she hunching over? I would say that might be more indicative of pain. As for Tramadol...it is impossible to give and, for the life of me, I don't know why vets give it to small dogs because there is no way it can be compounded to taste ok. I recently bought chews that I thought would work if they swallowed them whole...but they don't work. I always ask for other meds....but these days vets are staying away from the Tramadol anyway because the studies have shown it to be less effective. They often use Gabopentin along with Metacam. I have also used Bupranex in the past.
If you think it is painful for her, call your vet and insist on another pain med.
Here is a link to the story about my Teddy Bear in case you might be interested:
http://www.yorkietalk.com/forums/sic...ver-shunt.html