After 6 months, my knee isnt healing from a roadrash?

6 months ago i was on the back of my husband's motorcycle and we hit some gravel and fell and skidded. thankfully we were ok only both of our right knees were messed up a bit. we kept them nice and moist with neosporin 24/7 and they healed very quickly. on me however, the past month the area has been getting purple when i shower but would disappear when my knee dried and the last 3 weeks the reddish purple spot hasn't disappeared. my older brother thought it might be wet or dry blood under the skin and tested his theory by poking my knee with a needle. my knee bled, but not like he thought it would, so were guessing its dry blood. im just wondering why this thing isn't going away? its not painful, just annoying that it wont go away. do i need to just re-sc my knee and let it heal again? i should also mention that it doesn't look like a blood blister; it doesn't protrude out of the skin like in all the pictures i see, it just looks like a scab with clear normal skin layers over it.