Hello, Buddy's mom! Thank you for your question today.
This is such a common phobia--fear of loud noises like storms and fireworks. It can be quite a problem for some dogs, as you have experienced.
I am encouraged to hear that the benadryl works (but just wears off too soon). This is a good sign as it tells me he might respond well to some other types of medications too. I commonly prescribe sedatives for dogs with noise phobia. Some of the medications we use are valium or acepromazine, a tranquilizer. Both of these medications would sedate him more heavily than the benadryl, and would last longer.
There are some natural products that some dogs respond well to as well, such as a product called Rescue Remedy. I would recommend that you call your vet and discuss some of these options and if these types of medications are safe for your dog if he has any past health concerns. Your vet may be willing to prescribe you something to try. I am confident one of these medications will help and you will get better results. There is no reason he should have to find a new home, as I think this can be easily solved!
Here is a nice article on storm phobia. If you click on the "behavior" tab at the top of the article and look up noise phobia, you will find many articles with helpful tips as well.
Thank you, XXXXX XXXXX hope things go better with your dog!