My 9 Year Old Felt On Her Knee, While Riding

My 9 year old felt on her knee, while riding roller skates over a month ago, in the beginning there was some discoloration, and a little swallowing and sensitive to touch on top of the knee. Now there is no discoloration or swallowing , but still the sensitivity is ther and you can bearly touch the skin of the knee without a complain of pain