How To Treat Deep Wound Leading To Discoloration Of Cheeks Due To Injury?

My 2 yr old daughter fell off a toy in November. She landed against the side of an open closet door. Initially her cheek was red. Then a little black & blue mark formed. Since then it turned red. It felt like a little bump under her skin. Took her to doctor and she said it was likely tissue damage. It seems like maybe it was a deep wound and has been maybe working its way to the surface. Its red and hurts when she touches it. Not sure if its a contusion or hematoma or what. Not sure what I should do to treat it. Its from an injury 3 months ago so contusion was my guess anyway.