What Causes Bruising In Leg After A Fall?

I fell on my knee July 4th, right under my knee cap swelled up, and slight brusing. Went to my doctor and there was not anything broken. The swelling went down on my knee. I have slight pain in my knee still. my concern is that yesterday, July 12th, my shin started bruising and today, July 13th, I have lot alot of bruising all around the bottom of my leg and top of my ankle. Is this casused from the fall?