Concerned about rash

Hi,

I am sorry to post here because I do not have a dx at this point. Last year in June, I developed a quarter sized pink rash that looked like a lyme bullseye.  I was put on antibiotics and it got lighter.  I was breastfeeding at the time, the next month in July I saw a breast surgeon and had a mammo/ultrasound that was okay.  Two weeks later I found out I was pregnant.  This rash has gotten lighter and darker over time. I finally went to a derm in February and he gave me a cort cream and antifungal cream.  The rash went away all but a shadow.  After the birth of my son, it was back and bigger, like a silver dollar size but light, I took OTC cort cream and it is even ligher but not going away and the area hurts a little like a burn.  I am just wondering if this was IBC would I have noticed it much worse over the course of the year? How fast does it spread?  Was your symptoms like these? I guess I do not know what an inflammtory breast rash looks like.  Thanks for your help, going back to the derm on June 1.