Nipple on good breast gone dark after chemo

Hi

I had my first round of chemo last Friday all went well only side effect I have had is fatigue but noticed yesterday that the non mastectomy breast nipple has gone very dark has anyone else had this happen?

All good back to normal now don’t know what happened there with the nipple

After first lot of chemo last Friday all very normal until yesterday and seemed to be very lethargic hopefully better today 

it’s going to be a beautiful day so a walk in the sunshine should be healing