It sounds like sprain somewhere along the leg, right up to the shoulder joint. Not uncommon in lively piggies!
The front legs are the weigh bearing ones (the back ones act as propellers or springs), so a sprain tends to look worse when it happens in a front leg. As your boy is still happy to move around, eat and drink, I would not be too worried.
It can take a few days to a few weeks to fully heal, but if there are concerns at any point, please see a vet.
Recommended piggy savvy vets for Alabama:
Veterinarians: Alabama - Guinea Lynx Records