Hit On The Back Of Calf Causing Swelling Down The Knee, Soreness. What Should Be Done?
Considering the mechanism of trauma and your symptoms, I do not think there is bone fracture or ligaments/meniscal damage. It seems like this is only muscle contusion or strain resulting in pain and swelling which is usual sign of such injuries. If you experience difficulty walking, pain while sitting or at rest, or if you notice change in shape of calf muscles and loss of sensation, you should see doctor as there could be muscle rupture.
Until that you should rest, keep your leg elevated, apply some cold ice on it (not longer than 15 mins per hour), take ibuprofen for pain. This should heal in 7-10 days. If not, you should do ultrasound and knee x-ray to check for some more serious damage, but I do not think this would be necessary in your case.
Wish you good health. If you have anything to ask me, I would be glad to help.
Regards.