What Could Be The Reason For Swollen, Stiff Knee Even After Medication?

Hi i,m Rita 38 yrs old. Exactly a week ago i had an accident and squeezed by knee between 2 cars. According to x-rays nothing was broken. Thighs & Knee are very bruised, but i don't have much pain. I took ANCROXIA pills and finished them this morning. What's worrying me is that my knee is still very very swollen and very stiff.