sore on my cats belly

my cat is a 12 year old female. I noticed about a week ago she had a sore on her belly. It is oval in shape and about the size of a quarter. When I first noticed it was moist and almost reddish. Now it is pinkish with a little white circle in center that is almost like a little hole, almost the size of a dime. she seems to be ok other than this. Shes eating good and acting normal except for licking it a lot. There is no fur on it, just a pinkish fleshy sore. Never seen anything like this before on any cat ive ever had. Any ideas on what it could be? first I thought it was ringworm, but isnt crusty looking. Help!! Shes an indoor cat and hasnt gotton into any fights, so Im at a lost. I will try and post pics so you can see it.

Sounds like ringworm to me. I would take her to the vet.

Pics would be helpful. It would be best to take her to the bet. She will more then likely need some sort of treatment.