Whiteshark is right to mention shampoo, toothpaste and mouthwash although I would add soap as a potential culprit also as it does come into contact with the face through the hands, even if the face is not directly washed in it. He's got the right approach in listing all those potential irritants.
Those 4 are the biggest contact irritants for EC in my view especially if the EC is trauma induced from biting. A wound cannot heal if it is constantly being stripped back from irritants. I also think this is one factor that could explains Daniel Miller's healing. He applied huge amounts of barrier (in the form of aquaphor) to his lips so the hygiene product could not contact the wounded area to cause the damage. Once the wound healed he may have continued using the same hygiene product but because the wound had healed it no longer caused enough of an irritation to re-start the EC.
Quest it would help if you post a photo of your EC so that you can get some feedback.