Sorry to hear this. Angel had Giardia as well. She only had to be treated w/ a 1/4 tsp. of Panacur for 5 days and it was gone. I did a lot of disinfecting, washed her bum and paws, if necessary, w/ shampoo after a bowel movement and gave her a bath after the treatment was finished.
You can read about my experience here:
http://www.yorkietalk.com/forums/showthread.php?t=44285 and
http://www.yorkietalk.com/forums/showthread.php?t=45380.