[UConnJulie]

Well, not to be the bearer of bad news, but if it is full of blood, then it has been bleeding. And if nothing is broken, that usually means ligament damage (ACL and/or PCL). And a fully torn ligament will not hurt.

Swelling is a normal physiological phenomenon. There is higher pressure in the artery than the vein, so at the capillary level, the excess fluid gets pushed out. The lymphatic system is normally efficient at returning this extra fluid by a variety of mechanisms so we don't notice the swelling. However, in the case of injury, your body is sending extra blood to the injury site to send WBC and other things needed for healing. Increased blood flow = increased swelling. If you are not up and moving around per your usual, the lymphatic system has a harder time getting rid of the fluid.

Elevation is a great thing. Especially combined with ice and compression.
What are you doing for compression?

Other things that can help are ankle pumps (at all times).