What's wrong with my bubble eye goldfish's eye sac?

I noticed that my bubble eye goldfish has one eye sac that's filled with an orange/red substance and is slightly deflated. What could it be? It's only been a couple days, but I'm worried if it's an infection, I don't want it to spread to the other fish. It's a 60 gallon tank with 13 fish, 1 "sucker", and one itty bitty frog.