This past fall after a ride I realized the bit I had been using (basic western port bit) had a crack in it and had made a sore, I felt bad and thought I'd give his mouth a rest and use a hackamore... The first time I used it he was fine the whole ride but the last time we were cantering he randomly started breathing funny and almost seemed to panic (rasping breathing, mouth open, head low, and refused to stop cantering- he just completely tuned me out)- I was on an organized ride and I had MANY people look at the placement of the hackamore on him and they all said it was on correct, not cutting off his breathing or anything.
I stopped using the hackamore and went back to a bit after the sore was gone but since then when I say whoa or cue him to stop at the canter he lowers his head and it is like I do not exist. This is not always the case and most of the time I can EVENTUALLY get him to stop but it's like a constant fight and there have been times I have had to reach up and grab his head to turn him tightly to get him to stop before he runs over people or takes me into the street (he doesn't have the best balance and I'm a large rider and I fear I'll flip him.) In the ring he is a perfect angel so no matter how many times I try and recondition him to whoa in the ring he already gets it. He has that thoroughbred mentality of GO GO GO, and will go for HOURS UPON HOURS before getting tired this is great when we do our long trail rides, but no when he's not stopping at the canter, or I'm trying to get him to re-learn how to stop.
My horse that use to make me happy is making me not want to ride anymore...I just don't know where to go from here I feel like it's just getting worse not better, any suggestions would be appreciated. Has anyone ever had a problem like this after using a hackamore??