Ow...
First, waves of sympathy! Being denied your bike or a good run just adds insult to the injury, and it sounds like you're going a little stir crazy. I'm not a medical professional, so here's just some common sense from someone who's accident prone (I'm 58; I've been falling down and off things for most of those years, with no serious injuries, thank goodness.)
First, if in doubt, talk to your doctor or her/his nurse practitioner, if of course, you can reach one
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Swelling is normal. It's only been 3 days, right? You not only banged your poor knee hard, you proceeded to bike and walk some miles on it. All of this would produce soft tissue injury and swelling at least. If your knee or leg is red or hot, that's not normal and could be the sign of infection, so check with your doctor fast.
See http://www.merck.com/mmhe/sec24/ch299/ch299g.html for a good, quick overview, and see the link to sports injuries at http://www.merck.com/mmhe/sec05/ch07...075-ch075a-980. That recommends rest, ice, compression (depending on the injury, and probably not while you've got a lot of swelling), and elevation (RICE).
It sounds like you might force yourself to do a little more of the resting and elevation piece to good effect
. It's most likely the swelling that's making it hard to bend your knee (more normal symptoms). Getting off it, elevating it, and icing it will help the swelling go down. Depending on how fast you heal, and you probably have a good sense of this, if it doesn't start to feel better in a few days, talk to your doctor again.
I'm a big believer in lots of ice. Chopped up ice in a couple of plastic bags with a little water will wrap around your knee while you're doing that resting. If you have an old-fashioned hot water bag with a wide mouth, that's good, and if your cupboard runs to frozen corn or peas, a pack of them reserved for this purpose is perfect. Just label it "knee" and keep refreezing it to use over. Bang on it when it comes out of the freezer to loosen up the contents and vent your frustration. Put a dish towel betwen the ice-bag and your knee, and don't use the ice for more than 15 minutes at a time. I use ice until I don't have swelling any more, but some sources recommend heat after the first 24 hours or couple of days. There doesn't seen to be complete consensus on this, so I'd say do what feels right. People and injuries differ.
Did your doctor suggest ibuprofen, aspirin, or another anti-inflammatory? If not, and if you can take an over-the counter one, that will help, too. Follow the package cautions!
Good luck, and fast healing.
No matter how much the world changes, cats will never ride bicycles.