Nickle size bruise on inner left breast since yesterday--purple, red , yellow. been carrying babies not sore afraid of ibc. does this sound like that?

Superficial injury: With both sudden onset (since yesterday) and associated with the colors often found with a superficial bruise, it sounds more like a small hematoma. You don't describe how you are carrying babies, but usually this would be across ones chest, hence a likely cause. If this does not resolve in a week or so, it would be good to get it checked out to relieve your concern.

Contusion: Most likely a resolving contusion. Carrying children, especially squirmy ones may cause contusions and bruising. If this persists and there are other findings see your gynecologist.