My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. It will be my pleasure to work with you today.
It sounds like you need to do training with your boy. You definitely need to work with him on the leave it command. The following site goes over a good way of teaching the leave it command.
I'm also going to suggest obedience training even if the dog already knows commands. Obedience training not only teaches commands but establishes you as the boss and leader. As the boss, everything belongs to you including anything he has and usually they wouldn't dream of taking something from the boss or leader unless you were playing. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
The thunder is a noise phobia which is very treatable. This is really a common problem. Many dogs have reactions to different noises. This is really a problem around the 4th of July and fireworks. For things like thunderstorms, some people tape the noise and play it back at lower volumes while playing with the dog and providing positive reinforcement for the dog's lack of anxiety while the noise is played at low volumes. Positive reinforcement would include calm praise and hot dog slices or other tasty treat (not regular treats. You then gradually increase the volume slowly until your dog is desensitized to the noise. Your vet could prescribe a medication called Acepromazine, which is a tranquilizer. You can read about this here:
Another prescription drug would be Xanax but I have to caution you not to give any prescription drug to your dog without consulting your vet first.
Many people get Rescue Remedy to help with noise phobias. Be sure you get the kind that does NOT contain Xylitol. You can read about this here:
It may also be available in your local pet store as well. Benadryl is often used as it does tend to calm your dog. Benadryl can be given to your dog, the dose is up to 2mg per pound every 8 hours. Benadryl in not a sedative though so it won't put your dog to sleep. Leaving a TV playing loud also helps prevent your dog from hearing the outside noises. Another treatment is Melatonin which you can read about here. It has been shown to work well for noise phobias.
DAP collars might help a bit as well. They produce pheromones that mimic the ones produced by a nursing mom to calm her pups. It has proven to be helpful with this problem but was used in conjunction with desensitization so it is unknown if the collar or the training was the major factor in resolving the problem.
Give my suggestions a try. I do have an appointment this morning so will be gone for several hours but I can address any concerns or clarify any questions you have on this when I return. If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.