Ok so I ran yesterday, a really super easy 6 miles, after a scheduled down week of only 64 miles. I'm usually in the mid 90's. Anyways, I felt no pain on my run, and later on in the day, about 5 hours later, I stood up from the couch and felt pain in both of my knees. It is on the inside of both of them and by late afternoon they started swelling. I wake up this morning and find that my left knee is very swollen. Like very, visibly swollen. I'm icing them and taking ibuprofen hoping that the swelling and pain goes away. What could have happened? Why did both of my knees seemingly for no reason swell up? The only thing I know is that I ran in the same shoes I ran my last marathon in and at the end of it my right knee hurt in the same place it is hurting now, only not as bad. I have run in the shoes many times since that race and have had no problems. Also I'm in central Illinois where it's been in the single digits and running in shorts, could the cold weather have something to do with it? I go to school in Mississippi so the temperature change was abrupt. Also, it doesn't hurt to walk, just to stand up. Would I be an idiot to go run tonight if the swelling goes away? Anyways, any help would be much appreciated. I'm kind of freaking out cuz I really don't want to take many if any days off. Thanks...