Hi, my brother suffered the same kind of problem. The area around his belly button became infected, red, crusty and it just kept getting uglier. The doctor diagnosed that my brother became allergic to his jean's metal buttons ( I think it's in copper or something..). He recommended that the metal buttons on all of his pants be changed by plastic buttons, just to see if it would help. Well, it helped a lot ! His belly is now healed. You should try this for a couple of time, just to see...

Good luck