This is his belly button. Anyone know what this is. We don't have an urgent care near us and I can't…

This is his belly button. Anyone know what this is. We don't have an urgent care near us and I can't call the dr until Monday. Any ideas what this is. Is it normal? It looks like puss but also not puss? Should I pop it or leave it until I can get him in. I'm worried about the infection spreading if it is an infection.