It's possible that when being groomed something happened that was a little traumatic and it's sticking with him. Personally I generally prefer not to go to the groomers if I don't have to. I do however hate the hair in my bathtub. If you have a PetCo nearby you can use their tub, towels, and dryer for about $10. I like that because it more closely simulates a groomer's enviroment and can help desensitize them to the environment.
I would just go back to basics with it. Treats and gradually building up to what you want.
I would just go back to basics with it. Treats and gradually building up to what you want.