How to help fearful dog?

This is my little man Doug. Until recently, he was a happy guy who would never be more than a few feet from me. If I was sitting down, he was next to me. Then in May, a tree fell on our house during a storm, and Dougie was on the couch five feet away from where it fell. Now he’s afraid of everything—storms, rain on the roof, wind, even the regular sounds of the house settling. He now spends the majority of his time in my closet—or in the bathtub (pictured below) when he really gets scared. He comes out for treats, food and water and he’ll come and sit with me for a minute or two, but then he gets spooked and heads back to the closet.

This is no way for a dog to live. I feel so bad for him, but I don’t know how to help him. He has a thunder coat, a pheromone collar, two types of calming chews, gabapentin, and a new daily med that the vet says should start making a difference in about a month. I also bought a pheromone diffuser that’s supposed to help, but it doesn’t seem to.

I’m desperate for suggestions. I want my little guy back! TIA