Advice Please - Breathing funny and very unstable

[Richwright]

Hi All,
New to the Hamster world having purchased a winter white for my daughter.
So we have had Cookie since early December and she has been great.
Last week he was breathing extremely fast and just sat in the corner of her cage looking very sad and lethargic, we watched her carefully and saw her fall over a few times too. Once we got her out she seemed ok (breathing fast still). We continued to watch her and then took her to the vets. They said a respiratory infection and dehydrated, they gave fluids and antibiotics and said she should be ok but at these guys are so small of fragile she may not.
Now a week later and having given the antibiotics daily shes still not good, and last night she was on her side looking like she was about to pass and then put of no where leapt up and couldn't wait for cuddles, still breathing heavy too.
She is just not right and i wondered if anyone could shed any light on if they had had this with their hammy's?