Oh the cheeky little b*gger! Hope you're ok and your confidence isn't too dented. Don't know what got into the horses yesterday - I had my worst ride yet on Ronnie - total bucking bronco at anything (bird, hedge, funny-shaped cloud - who knows?). I managed to stay on but that was more by luck than anything. Felt very shaken last night and I'd imagine you did too. It's gutting when they do something so out of character. Do you have a friend who could get on and put him through his paces at the next show just to check he's got his sensible hat on?
Also - was anything different with your tack? Had you by any chance gone without a numnah or anything like that? Can be silly things that upset them at shows...
Hang on in there and don't be put off. My mare was like that when I first had her and the secret was in doing loads and loads of working in at trot. If I cantered too early she would put in a few bucks. She turned out to be a complete star and we won at county level several times, so grit your teeth and put it down to experience!
I can sympathise thought with the falling on your face in the arena, my mare actually tripped over and we both fell down in the sandschool one day and I had a mouthful of sand which was most unpleasant!
In answer to some of your q's, no not our first show, we were at the same venue in Jan & Feb doing dressage - but first time in a warm up with quite a few horses. Yes first time jumping at a show since I've had him and yes I had taken his numnah off, I'd left his prolite pad on though, but maybe something pinched as he landed over the fence?