IslandGirl,

I am not sure what trefoil hay is (different sides of the country) But I would suggest an all grass hay diet but it sounds like that is what he is on. He looks great by the way. You mentioned that he only does this when you are in a group... So he doesn't rear when you ask him to stop and he is by himself, he just does this while he is in a group.. When he does this are you the only one stopped and the others go ahead? If so sounds like he is a little herd bound when you are with other horses. I had a walker once that when we were in a group he had to be in front and was a bear to ride if he wasn't the lead horse, but when we were by ourselves he was quiet and walked slow and calm. I had some tired hands but I made sure that I rode in a group even if it was 1-2 other horses and made him walk behind, and not right behind but back a ways. If he only does this in a group I would try working him as much as possible around the other horses. See if they would have a few of them stand 30 feet or so away and you make him stand quietly if he begins to through his tantrum then begin do the circling exercise. The only other this is you may have to enlist the services of a trainer in your area. But good luck and hope this helped.