What Causes Low Back Pain Radiating To Legs After An Injury?

My husband was in a car accident two weeks ago. Minor bumps/bruises. Right knee was bruised and swollen. Now, almost two weeks later he woke up this morning with a right swollen ankle, on both side of the ankle and bruising. The right calf is also swollen now. Also experiencing low back pain with pain radiating down both legs to ankles. Is this normal or should he see his doctor again?