S.W.
I had a rash like that, that started when I was BFing. Since then, I've gotten it a couple more times. I also eventually used hydrocortisone cream on it. It took a very long time to go away. Unless it starts getting worse, I would just keep treating it. Skin rashes, in my experience, can just take a long time to clear up.
One thing to watch for. I developed an allergic reaction to the hydrocortisone cream. It now causes small fluid-filled blisters on my skin that are incredibly itchy. So now, I can't use the cream anymore.