A few weeks ago I fell onto a stair and my knee was pretty badly hurt - the next day the knee had bruised and it was a dark purple, but there was a white spot in the middle of the bruise and when I touched it it felt kind of...numb...I guess you could call it.

For over a week my knee hurt like crazy when I touched it but other than that I could walk normally.

The bruise is gone now and my knee is almost fine except it I knock it hard enough or lean on it too hard...

The problem is when I sat down today I realised there's a spot that moves around in my knee that wasn't there before and it's not like that on my other knee. I'm worried about it and I don't know what it is, can you help me please?