if he has just shoes behind and shoes AND pads on the fronts, the issue could just be the hard frozen rutted ground. that stuff if heck to walk on for ME let alone a thin soled horse that is prone to bruising. even if he is normally fine on the hinds in normal conditions that frozen ground especially if rutted is sharp!
Hope all is well and it is only hood bruising and no foundering!
*Member of the Quality Free-Choice Hay/Pasture Feeders Society* *In Favor of Turning horses out as long as Possible*