Is there something wrong with my scar?

In December, I slipped on the ice while running to the bus stop, and tore open my knee pretty bad. I just put band-aids on it and neosporin, and cleaned it out a lot to take care of it. Now, I look at my scar,and it is kind of poofy, and purple. the skin on and around it is kind of smooth where it's sort of healed. I put Vitamin E ointment on it, but it doesn't help. Everyone tells me I should go see a doctor about it. What do you think?