I have only ever seen a goat be sick once, and that had bloat. All frothy grass came out of her nose and mouth. I would have thought the pig food would have gone through her system by now, so hopefully she is feeling better.
I would be happier if she was cudding, but like you say, she needs to be eating first. At least she is drinking, but I suppose the pig food has dried her out. I would tempt her with things like digestive biscuits, cream crackers, a banana, anything to get her eating again.