It can be expensive, but you might want to take him to a behaviorist. I ended up taking my rescue to one after I got her due to high anxiety and fearfulness. She was scared of EVERYTHING. She didn't bark or growl she was just scared. She would sit on the couch and just shake. And she freaked when I got into the shower as well. The behaviorist helped quite a bit. Molly, my pooch, ended up on medication (prozac) for a bit, but after she was taken off it, she was better. She will never be a "normal" dog, but she is our sweet soul. Good luck.