It looks like it may be ringworm. The name is misleading. Ringworm is actually a fungal infection that IS TRANSMITTABLE to humans, so please be careful. It would be best to see a veterinarian as soon as possible. If it is ringworm there is a cream that is also used for humans that is sold at lots of places, CVS included. Do not take my word for it because this could be any number of diseases or infections. Check your other piggies, if you have any others, to see if they have any other similar symptoms. Good luck!