I have a Cairn who is crazy-neurotic when it comes to thunder storms and fireworks. Long story short, we were on vacation and the poor dog was crazy due to the all the fireworks. I called the vet and she advised Benadryl. Later, we got some doggy “feel good” pills that do a better job. So, yes, you can give Benadryl but the amount is limited (like with all drugs). Just a thought.
We started to tranquilize it in the last few years.
My mother simply gave it a shot before the family went out, and made sure it was still breathing when the family returned.
My current batch of dogs are quite used to big bangs. It is a training technique. Bring the dog to heal on a lead tied to your leg, and bang off a bunch of shotgun rounds.
The pup will freak for a moment, then look into your eyes. Look back, then fire again... They get the message that if you are not scared, then they shall not be scared.
My grandparents and parents have trained animals for 40 years.
I currently civilize feral cats, for fun.