I just wanted to share that after 21 days of medicine and worry and 3 vet appointments, my hedgehogs were finally given the all-clear at the vet this afternoon!
Puff still has a slight head tilt but the vets have concluded this is either permanent from inner ear damage or that Puff is prone to WHS, that the URI amplified her early symptoms and there's nothing more to do than keep a close eye on her. I am running fecals on everyone too just to rule out any internal parasites as it's been difficult to put the weight they lost back on them, but so far Puff and Oakley are negative, and I just have to wait 'till I can get a fresh sample to run Chloe's on Monday. Chloe is showing some bald-patches and dry skin so the vet prescribed me some heal-x sunshine factor and I'm going to treat all 3 with revolution now that they are healthy and eating again.
Best of all, all 3 hedgies are URI free! Hooray!
Thanks to everyone for their advice and support!