Could I have a bruised bone?

So yesterday, long story short I slammed my kneecap REALLY hard into a door. I wasn't expecting that much pain but I lite really had to fall to the ground because I couldn't stand. I expected for it to hurt for a few hours but it's been a day and it still really hurts. It doesn't look swollen though there was a small bump yesterday and I really don't see any bruising. Is it necessary to go to the doctor or should I wait a few days to see? I'm trying not to walk on it too much and use my right leg to bend and keep my other leg straight as possible when I go down the stairs, if I bend it thats when it hurts. Or touch it.