marathon training

So,
Marathon training is not going well. I have hurt my knee. Came back from a small run (only 6 miles or so) only to find that my kneecap was all bruised looking. 48 hours later and its still looking dodgy. This is very frustrating. I may have to stick with the half marathon instead which sucks because I wanted the challenge of the full thing. ARGH. We'll see.