[souffle]

I'm sorry she's not feeling so well. There are a few things to consider. It could have been that something else was the cause of her fur loss rather than mites and this has now progressed. A patch over the scent gland only is unlikely to be mites and more likely to be hormone related.
She may have reacted badly to the mite treatment. It can happen in some small animals.
It could have been the handling has caused some internal problem / rupture and this would be quite serious. It could even have been a small stroke. Most hamsters who get through 24hrs after a stroke will survive it.
Check her water bottle is working well. give her a small dish as sometimes they cannot stand up to use the water bottle and become dehydrated. You could drip or spoon feed her some fluids - try some child rehydration fluids or a teaspoon sugar and a pinch of salt in a pint of water would work.
Infections / other diseases and problems can escalate quickly especially if she has been under stress at the vets so keep her very calm.
I would offer her some baby food in a low saucer (Pringles lid we use) and also some small soaked stuff like cheerios are liked. You could try some little bits of cucumber too. Anything to get her eating again.
Is she swollen at all? Weight loss? Breathing OK? It was extremely hot on Sunday and this has stressed may animals.
I'd phone your vet for further advice and see how she goes over night with the fluids and baby food or readybrek.