Why is there a huge bump on my shin after falling on a hardwood floor?

Localized Trauma causes the breakage of small capillaries close to the skin and around the injury site. These broken vessels leak fluid into the local tissues which can look like a bump, or if they leak blood, like a bruise. Typically, these bumps/bruises will aid in the healing of the injured areas and will go away within days or a week. Apply ice to reduce inflammation and avoid reinjuring.

I agree but also if you are on blood thinners or take aspirin sometimes the bump become more pronounced because of bleeding in the area