When your knee is inflamed are there meant to be bruises?

my knee started to look weird a while back and it hurt when i knelt down. i went to the hospital about it, they said it was inflammation and i had to rest it. but i still have to do p.e and i need to keep fit. now it's starting to look worse there are a few bruises around the knee cap and i just want to know if anyone can give me a heads up on what they think is wrong with it.