Pig feet (new to pigs)

Hello! I’m still new to pigs so any advice is much appreciated. I have two- 1 year old kunekune brothers who free range on 2 acres during the day and then get put up for the night. One of them has recently started limping and was quite concerned. I checked under his foot and saw this “hard lump” under his foot. I know it’s time for a trimming but what would cause this harder spot under his foot? And looks like it’s almost splitting as well. I’m kinda far from any vet/farrier so if it’s something I can do please let me know. If not I’ll probably have to try and get someone out to check him out.