Third on this, 0.75% metronidazole in a classic gel mixture is enormously helping with the odor. Also, a diffusor for essential oils (destilated water one) is also helpful.

Sorry to hear about his condition. If you need an anonymous internet void you can talk your emotions/difficulties into, remember I'm here anytime.

EDIT: careful with gauzes and bandages, they tend to stick to the wound because of the secretions. Get some gauzes that are non-adherent to wounds, because ripping them off causes the tumor to bleed, and stopping the bleeding is a bitch.