A "problem horse" that shouldn't be a problem....?

Try to think back to the day he bucked... was it simply a buck from his high spirits or did he pin his ears back as though in pain. if its the first one then most likely it is you who has lost confidence in riding and in that case defiantly go to some lesson and brush up on your skills horses can sense everything and its most likely he can now tell your scared on him and because you have a great bond on the ground he really trusts you so if you get on him scared or nervous hes going to think there is something to be scared and worried about. If its was the second option with the ears pinned back then perhaps he spooked at something or maybe his saddle pinched him and now Associates you with that but that is unlikely as ye have such a great bond on the ground. you say he is fine for other people so its unlikely to be pain related. but its hard to tell without seeing. So ya go get some lessons and maybe bring your horse too after a couple weeks ( maybe longer depending on your riding standard) it will be great to have a trainer there to help you too.Also finally he could just be taking the piss and sense you aren't able to control him and in that case bring him to your lesson and get firm with him he could just need some good schooling. Don't worry i am sure your problem will soon be sorted and ye can go back to the way it used to be. good luck