Do you have a GP who's happy for you to call? If you have a good relationship with them that might be a good idea. My GP always says they are ok as long as they have some 'spark' about them. If they are so lethargic that they don't respond to you then they are headed towards or are dehydrated. I have found this to be a good guide for me, but I imagine you are better qualified to judge it than me (your are a nurse, aren't you?).
Is there anyone who could drive you to the GP or to the hospital? Can your DH knock off work yet and take it as sick/compassionate leave?
Hope she improves for you soon.