Sore lump on muzzle I presume from gentle leader

[Notonaschoolnight]

We've been using a gentle leader for 3/4 weeks a couple of days ago I felt a lump on her muzzle I stupidly thought it was food or a knot so gave her a good brush. She doesn't like the gentle leader and really didn't like it yesterday and today so as I took a closer look I realised she had a raw looking little lump where it rests.

I've never had a dog before I thought I should take her to the vets asap or is that a bit drama queen is there a kind of ointment I should try first. I really don't know