This could be caused by low calcium levels, as she is feeding her pups right now. Producing milk puts such a strain on the female's calcium reserves, that sometimes the metabolism cannot keep up. This might sound like not much, but it can be life-threatening. It is known as Eclampsia.
I don't mean to scare you, but if it IS this condition, and it is left untreated, it could seriously compromise her. The best thing would be to try to get her to a vet as soon as you can, even if it means a long drive. I don't know how practical or possible that is going to be. Surely there is an on-call emergency facility attached to your regular veterinary surgery? If you ring your vet, even though it is Sunday, there will be a message no doubt, and most likely, an out-of-hours emergency number to call. Call it. At the very least try to speak to someone for advice.
(Of course, it may not be Eclampsia. It's impossible for anyone to diagnose that from a distance, on this forum.) But to be on the safe side (and the symptom sounds classic) she needs to see a vet before Monday.
My apologies because I have only just seen your post. I noticed that your question was posted Saturday. I hope all is well.