You're speaking with Dr. Michael Salkin. Welcome to JustAnswer. I'm currently typing up my reply.
Carys, can you upload a photo(s) of this sore to our conversation? You can use the paperclip icon in the toolbar above your message box (if you can see that icon) or you can use an external app such as dropbox.com/
I can be more accurate for you if I can see what you're seeing.