Call your farrier back. is there any heat in the feet? is it all four/two/one?
It could be he/she may have taken off a bit too mch in which case all you can do is hose the feet and paint on something nourishing like cornicresine/hoof heal/kevin bacon/effol etc and wait
It could be sole pressure which normally rights itself within a day or two, cold hosing really helps.
It could be a nail prick wich if still has the offending nail present will turn into an abcess so that needs removing, if the nail was already removed then it needs keeping clean as could turn into an abcess
He/she may have changed the angles in the feet and sometimes it takes a day or two for the hrose to get used to it and it feels its feet for again a day or two.
These are the more likely reason but i suggest calling your farrier back anyway especially if its possible its a nail prick as the shoe may have to come off for polticing, and he/she knows your horses feet.