Aw. Poor mother pig. Poor little piglets, too.
I too would have the piglets under a lamp, and maybe try now to get them lapping some milk - before it is really urgent as when they all need it at once, it'll be hard to meet their demands. They'll happily go back to Mum if she's okay, but in the meantime you've started the not very easy step of getting the little ones used to another means of taking in nutrients.
Can you try banana for the sow? When ours have been down, we have found that we could pop small sections of banana in their mouths and that it stimulated an interest in drinking, too. It may not be the right thing or what she most needs, but for sure, it won't hurt. And we have found twice that it has re stimulated a sow who seemed to feel too poorly to try to eat or drink.
Give her a stroke under the chin from all the Cinderhill Farm piggies too.