Fell on it in my kitchen a few hours ago. I can get around, gingerly; surely nothing’s broken. Not having had many injuries in the past, thank goodness, I don’t know if it would be better to rest it or exercise it. What say you, if you know about these things?
Rest, ice & elevate. Move as much as it will let you, but don’t overdo. You can in fact crack a kneecap so if it isn’t significantly better in a day or so getting an x-ray might not be a bad idea. Oh, and if you can, take some tylenol. ***
*** I am not a doctor, this is just what I would do for myself with a similar injury. Seeing a medical professional is never a bad idea if you have hurt yourself and aren’t sure how badly or what to do about it.***
Oh, this is exactly what I needed to know! Many many thanks.
Use the mnemonic R.I.C.E. Rest, stay off it as much as possible; Ice, 10 minutes every couple hours, be sure to put a cloth between the ice and skin to avoid burns; Compression, an ace wrap. and Elevation, lie down and try to keep it above the level of your heart, as often as you can.
If it continues to swell, turns color (red, mostly) of you can’t bear weight on it, see a healthcare provider.
Pro tip: A bag of frozen peas works well for icing knees. Or other non-flat surfaces.
Thank you for so much good help. I’m really glad you’re a member here! 
Thank You! !