He is rubbing it off of something. Now that it is an open wound its getting worse without treatment. I am not sure what can be applied right on the nose but there has to be something. Usually Neosporin (WITHOUT pain reliever) is use to prevent infection and promote healing but I do not know if it is Ok to use right on the face. You can email Dr Frye and see if he can recommend a treatment. Sand a pic to him in your email and a detailed message about when you first noticed it and how it has progressed.
Here is a link to info on Dr Frye: Frog First Aid Medications - Being Prepared