How long is the recovery time after a cat is treated for giardia?

Our newly adopted 2 year old cat was diagnosed with giardia about a week after we got him. He's been through a course of medicine and has been kept away from our dog and other cat. After he was done with his medicine on Tuesday I bleach cleaned the room he's been quarantined to and bleached the litter box, bowls, etc. I've been obsessive about cleaning his box. It's Friday and there's no improvement in his diarrhea. He is using the box (before he was diagnosed he'd had a couple of accidents outside of the box) and it doesn't seem to have the horrifying smell that it did before he was diagnosed, but there's no improvement in consistency (it's like a cow patty) and he goes more frequently than he did when he was on the medicine (2 times at night, 2 times a day). He is starving all of the time, probably because his food is going right through him. He has a vet appointment tonight for boosters and I'll ask, but I called earlier in the week and really didn't get much input other than he'll need to be tested again in 2 weeks, no improvement is not a surprise, and expect to have to do another course of medicine. So, my question is - if you've had experience with this, when is a reasonable amount of time to expect improvement? Is it possible the giardia is gone and the continued diarrhea is a side effect? If so, how long could that last? I've been adding a probiotic and a couple of teaspoons of pumpkin to his food once a day. We've used pumpkin to help pets with diarrhea before. How long do I have to keep this poor guy quarantined? Could our dog get it if he comes in direct contact - you know how they like to sniff the worst places.