My boyfriends penis is going black, what do I do?

My boyfriend has this penis, and it was really nice and well groomed, all shiny and brown and perfectly formed. But 2 weeks ago, the helmet end has started to go black and moldy, and has a weird smell, smells a bit like steaming flannels and fishy clams so I don't know what to do. It looks really flaky too, and he picks the flakes of so its starting to bleed as well, what do I do? I cant describe the blackness, it is jet black, looks moldy basically. Please help.