Please help!!

This is pretty boy. He's a pullet, I assume only a few months (not sure exact age) but he hasn't been walking nearly as much, and seems to be in pain / uncomfortable. I looked at his foot and found this weird bulge on the side. No puncture wound from what I could see, just the swollen mound. Anybody know what this is, and if so is there any way I can help him from home?