How can I get my dog to go outside again?

I have the most adorable sheltie corgie mix. We found him as a stray and he'd been outside long enough to develop a horrible fear of thunderstorms. We've had him for a year and things have been great. But since Independence Day and all the fireworks and storms that have moved within the area he has begun to refuse to go outside. I've tried coaxing, carrying and nothing works. He goes outside fine in the morning but after one pm, forget it. Does anyone have ANY suggestions how I can help my loveable Swiper learn to love the outdoors again? i've heard aboout desensitization (play recordings of thunder til he gets used to it) but it sounds so cruel. He even trembles when someone's auto bass is too loud. HELP!!!!!!

it's anxiety....see what the vet says (you may need to find one that is a behaviorist).