Hi!
I have had a scab in my right nostril for the last 40 years. My doctors put me through the same thing you went through; with the silver nitrate etc. Nothing worked. Finally my doctor prescribed Mupirocin ointment 2%. This worked great! It cured the sore up in about a week. However, it always comes back when it's really cold out or I'm around a lot of traffic or a parking garage or two. I keep refilling the ointment and using it whenever it's needed. I've gotten so I put the ointment in my nose especially before going out in public whether there's a sore or not. It's works good as a preventative medicine.
Good luck!
PML