Uhmm...giardia anyone?

[treeling]

I took Dover to the vet today.  He's been having loose stools for a while.  I think a few weeks, but my husband says longer.  We were sent home with Metronidazole and sent the stool sample for testing.  The vet thinks there is a possiblity for giardia as Dover is a shelter cat, and his sister Shya whom we have had for about 2 months or so, was also a rescue.  Has anyone here had to deal with giardia?  We will have the test results back tomorrow, but in the meantime, what should I do?!  I hope the Metronidazole fixes whatever the problem is, and there is no giardia, but I'd like to know my options anyway.

Edit:  He had a bowel movement tonight that had bright red blood in it.  I'm going to call the vet in the morning.  I'm freaking out here.  Any words of comfort???