So my gelding has been fine left in his stall for many years at the trainers and if too hot or too cold he is inside at home. About three years ago he became buddy sour ONLY in stall alone. It was a new trainer and at first he kept him outside. The last two weeks in August he put him in a stall and at eight he started weaving... at the show he was bent in the stall (he had no buddies at the show) and his attitude riding is cranky with being in a stall. At the show I tied him to the trailer and he was better. Now at home he is fine in the stall unless we let his buddies out. So new places no buddies he gets upset and at home if let buddies out.
I already am having the vet come out and plan to check for any possible vet issues... but any exercises for the stall piece. If I am riding him he is not buddy sour. The stall is becoming progressively worse. I could just leave him in it but since he weaved for four days before the trainer put him outside I do not think this method will work.