Just got back from the vet, and it is a nail infection. I wanted to give an update in case this happens to anyone else's little loved one. The vet cleaned and clipped his nails and sent us home with antibiotics. One pill every morning and night, and clean with mild soap every three days. She recommened Spectrogel, but any mild soap will do. We are going back next week to make sure the antibiotics are working. She said it is common with older cats, they get a bit of bacteria in there and stop cleaning and that is what happens. Which is strange because my cat is a clean freak, always washing his little white paws. But perhaps he was just washing the fur and left the nails alone. At least now, I will know what it is if this ever happens again.