Does A Painful Bruise Formed Due To An Injury Require Medical Attention?

so, a couple days ago I lost my footing on my stairs and slid on my bottom hard down three stairs. the bruise has gotten worse, as I expected, but now there is a giant red area in the center of the black bruise. the bruise covers the top half of my bottom on the left side. it hurts to move like walking or moving positions when I m sitting. it is also hard to sit down and stand back up, but only in the area of the bruise itself. I m just wondering if this is normal or not.