Is knee swelling after fall normal?

Last week I fell and hit my knee. It is bruised and swollen. There are no breaks or cracks in the area. Today the bruise on my knee is starting to fade but the swelling is hard. Her legs can walk as usual, but sometimes it hurts, she can't straighten and feel pressured in the swollen part. Because the swelling is hot and hard. Kdng2 is tired and throbbing. When she wants to straighten her legs, she will crack her knees and feel heavy. When I sit down he is depressed in his knees. Is it dangerous or is it normal to get hit?