My 15yo quarter horse gelding that I bought about three months ago has recently started pining his ears and threatening to buck when asked for a trot. I thought it might be his saddle so i rode him bareback and it made no difference. He also has a very choppy trot that is hard to sit. He also does not seem to like the bit that he came with I’m thinking of trying a less harsh bit, just not sure what one. it is a tomb thumb bit. I am currently teaching him neck reining and he is learning quick but after a while he tries to pull on the reins and walk back towards the barn.