What Causes Light Red Patch On Side Of The Breast And Bumps Around It?

Hi,I have noticed a pink or light red patch on the side of my right breast about 7 days ago. It is not sensitive to the touch, there are slight bumps near the patch. I have started a new regimen of HRT about 2 weeks ago and noticed an increase in sensitivity since then.

This morning however, I can see that the patch has increased in size. My doctor has prescribed antibiotics and anti-inflamatory for a week to see if that helps to reduce the redness, he does not think this is a skin problem but comes from under the skin.

I am very worried about IBC. Are there other possibilities to explain this redness ?

Thank you for your time !

Catherine