Some bread, well soaked in water might encourage her to take some fluids.
I think If I were you, I'd keep a close eye on her see how she is this afternoon. I've had pigs looking unwell when it's hot or they have had a busy day and a few strawberries and a tummy rub have had them right as rain.
My vet is very good as giving advice, where he can, over the phone (and when he isn't HappyHippy is!
), so if not better after lunch I'd give them a call