Ok so today was horrible. I decided to go for a ride, got out there he was being so good tacked him up and rode him down to my friends paddock and he didnt put a foot wrong which I was very impressed on. Took him into the smaller arena went for a little trot and he was very good, did test me out but I always expect that from him. So my friend and I went for a ride through the aggistment to where the gate is on the other side. We got to it, rode through and went on walking around the arena warming the horses up. About 10 minutes into it I was walking muss and it was a flat surface and he tripped over air, his feet or both(not entirely sure which) and went right down, and all I thought was that he was going to flip over ontop of me but he hit the ground and staggered up but id lost my stirrup and my reins and had slipped off the side but was holding on and he panicked and started trotting and I knew if I held on he would have just freaked and gone faster so I dropped hit the ground with a real thud to the head. So glad I ride with a helmet because even with the helmet on I've defiently hurt my head though I don't think im concussed or anything(fingers crossed) but anyway so I just laid there for a few mins, muss settled and stopped and my mum caught him and was freaking out because well yeh im her daughter and was asking me how my back is coz I have metal rods in there. From what I've found so far I have a lot of scrapes and soon to be bruises, I stabbed myself with the pommel bit of the saddle in the gut so its extremely sore and going to bruise bad, my finger is fully swollen possibly broken or dislocated not sure, my heads throbbing and my backs quite sore. Though my gut and heads probably worse off. But that's not the worse thing that happened. I got up, got back on muss and walked around a bit, did some trotting, took him over some poles on the ground and I felt this weird feeling and my friend, an experience rider, I asked him if he could jump on muss as sometimes he's gotten on for me and he said sure and offered to take him for a canter. So I said sure that wuold be great and held his horse for him and he trotted muss around and muss was doing great, looks calm relaxed and then shaun asked for him to canter and that's when everything happened all at once. Muss went from calm and relaxed to a bucking bronco/ hopping kangaroo. Shaun was off in seconds and he hit the ground hard and was groaning so loud we were looking for a phone to ring an ambulance I was freaking out and I still feel so awful that he got hurt. I've never seen him do anything like tthat. He got up and said he was okay abit sore and had blood in his mouth but he said he was okay and got back on his horse but I felt so horrible about what muss did and that i'd asked him to get on and I took muss back to the other arena, tok him to the round yard and got on just walked him around for a few minutes to show it wasnt going to get him outta it and then I got off took his gear off and free lunged him at a trot. So now i've gotta make a decision: get a trainer to help me with him, which I've found one whos helped me with him before and I really liked, or sell him, find something older, more experience and smaller. So now I really gotta try and decide and my mum is on the verge of selling him. He's a good boy but today has really shocked me and I don't know what to do. I don't blame him at all for my fall, well I mean he coulda picked up his legs and not been such a silly boy, but it was an accident and he didnt intentionally hurt me. But he intentionally kangaroo hopped with my mate shaun and shauns about 30 and knows what he's doing and im 17 have only a 3 years experience and not with young horses and im only small so I really don't know what to do. Its between getting the trainer to help me or to sell him find something quieter to get my confidence back on.