Yes she is indoor onlyIs she indoor only?
It looks worse in the picture the sore is flat no real depth to itWelcome to TCS! I'm glad you joined the site and came here for support.
Both of the above members have noted good questions. From your pic the sore looks a bit deep. If she goes outdoors it could have happened there. I would call your vet to ask their advice, possibly send the pic to them, and ask whether to put something on the sore or bring her in. Please keep us posted on her progress.
It kinda just appeared she does run a round sometimes , it’s been there about a week I think she is making it worse because she keeps licking itHi!
Do you know if the sore spot showed up, and then she started licking it, or did it occur because she's licking it?
I was wondering, does she run during play, around and under things? Could she have scraped her back while "ducking" under something?