Bad timing!!

Two weeks ago i helped out my very kind sponsors Fatface at a PGL holiday camp they were helping promote. I had a great time trying all the activities, meeting fab new people and guiding beginners around a simple off-road course. It was here, with my low boredom threshold i decided to practice some technical riding, jumping from one set of roots to another. After a few goes i must have lost concentration and ended up smashing into a tree with the right side of my body. I finished the ride, feeling very bruised, shorts ripped and with a very sore knee and back.
The following day i trained but only gently and felt very stiff, but things seemed to get better during the next week.
In Germany last weekend the knee injury was aggravated with the long, fast, rooty, off camber descents on the run course. So much so that i was limping the following day. I first tryed to run this Wednesday and couldn't even manage 400 metres, before again limping home in agony. That evening it swelled up worse and i could barely walk. Thursday it hurt all day, even when pushing off the wall at the swimming pool. Today I have been pummeled by the physio, popping ibuprofen and Maximuscle ache-free like they're going out of fashion. Sitting here now with ice pack on.
I had been looking forward to UK Xterra for months, travelled down to Wales twice, ridden 3 laps of the course, checking lines... I'd even trained through Germany a bit and planned to rest this week. I am absolutely flying on the bike, but now can't even run 400m!! Still got 36hrs, will try to run tomorrow afternoon, to decide whether to travel down. Please if there is a god....