Charging about like usual but not eating all the food?! Sounds lime normal behavior with disappointment at the food.
Even frm the same brand not all food is created equal, its cheap crap made with the cheapest crap available.
If they are eating all the good stuff they are fine. You also said between gales I fed them, pigs don't like crap weather either so after a quick bite they headed back in.
Dont start using drugs unnecessarily.
Go buy some barley they will eat that with gusto and if they don't then you can worry. But only if they have eaten nothing else and the weather is lovely, oh and they are not in heat.