Suggest Treatment For Bruise On Forehead In A Child

My 9 mth old bumped his head on the side of a bookshelf. he is a very active baby and bumps his head on stuff all the time. A small line bruise appeared and I applied a cold compress. One of the spiderman ones from the drugstore. I put it directly on his forehead for less then a minute and today he woke up with a large red mark where the compress was. Did i damage his underlying skin or cause frostnip to his forehead? If so should I do anything now to it or leave it alone? he doesn t seem bothered by it when you touch it.