I am so sorry your pup is having some issues. I have linked an article here for your perusal;
Dog OCD | Symptoms
Something for you to consider, and I'm a little surprised your vet did not mention this to you.
I believe a behavourist is a good option. How-ever perhaps seeking a second opinion, from a INternal Medicine Specialist, would be a good idea. As the article says, there are medications and other therapies that might help him. There also could be an underlying medical condition that has yet to be found, that is either causative or contributory to his behaviour.
Please let us know, how it goes with Bubba