Purple Scar Won't Fade

my son (5 years old) fell off his bike 3 months ago and had to have his cut (above his lip below his nose) durabonded together by the Dr. There is now a bright purple raised scar that will not go away. I put mederma on it every day multiple times. The rest of his scars from the accident are fading away and are not as purple as this one.

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