
The only experience (and I hope it stays 'the only') I've had with Giardia was with a 4 month old puppy we bought in. He had loose stools, with occasional bloody flecks in it too. So I collected a sample and had it tested and to my horror it came back positive for Giardia and roundworm ova too. His breeder, who I knew well, said she'd wormed him (at least for everything other than Giardia which she denied any knowledge of having in her kennel!!). He was treated with a high dose of Panacur which didn't work for the Giardia so he was put onto Metronidazole (which is Flagyl) and we then got negative fecals. However, after that, he continued to be firm, normal in the morning but far from that by the end of the day. I understand (but didn't know until this because we'd never had this) that most of the protozoa is killed off but those that are not burrow into the gut and remain there inactive unless the dog is stressed. Nice. With all this continual bad stool production I took him back, and back until finally one of the vets from the sister practice was on duty and gave him an antiinflammatory shot and onto Hills I/D He suggested I make up a fish and potato diet (coley - mashed potato) which worked like magic. I eventually switched to Arden Grange Sensitive (fish, haddock and potato) which is more convenient and has all the extras I could give him in a home-made diet. He's been fine, other than the occasional tummy upset, which my Whippet had at the same time, for years now. I do try to switch him to another perhaps less expensive food, but every time he tends to be softer than I like. So if it keeps him regular, so be it - it's worth the extra cost to keep him away from the vet.
Re Giardia - he must have come here with it, despite his breeder denying this, because I'd had an oldie here before him who was fine, and my Whippet, who I had tested after this appeared, was always negative. It's found in standing water (it was February when he came to us and everything was frozen even if there was no standing water outside here in any case). I used Jeyes Fluid to clean up outside (to heck with the grass) and made sure we both washed our hands very regularly - it can transfer to humans. To be kind to other local dogs, I'd not take her out off your property until you start getting negative fecal tests. Insurance - don't know, you'd have to check
Puppies will mess in their beds if they are not taken out often enough. Adults don't normally mess where they sleep but if a puppy, who physically may not yet be able to hold, feels the need and hasn't yet understood you will be letting her out often enough, they will just empty. Your vet is right - she's just a baby. I'd check she doesn't have a UTI going on - there's no point 'training' if she can't help what she's doing.