What Causes Red Patch On The Breast?

Hi, For over a year I have had a red patch (rash?) on the surface of my breast. I want to be clear, it s never been itchy or elevated. It is not under my breast or where my bra rubs. It was smaller when it began, and I saw a dermatologist. She said I wouldn t worry about it and gave me hydrocortisone cream. The cream did not help. Since then it has grown. I ve used steroids, anti fungal creams, roseaca gel, tea tree oil....any anything else I could think of. It continues to grow. No irritation. No google images look similar. What could this be?