What Causes Itchy Hands, Heart Palpitations And Excessive Sweating?

Question: Maybe you can help. My husband has been having, what can only be called, theseattacks. They come out of nowhere. First, the palms of his hands start to itch. Then, his heart starts to race and he starts to sweat. The majority of the times, they'll hit him in the middle of the night. But, last night he had one before we even had dinner. This one was bad. He got the shakes and couldn't stop shaking for over an hour. When they first started, we thought he was having some kind of allergic reaction, so, we kept a diary of everything that went into his mouth. There's been no connection that we've been able to find. He will take a couple of benadryl and they help, but, he's pretty wiped out by them for a couple of days. Like I said, we can't find any kind of commonality to link these to. He doesn't smoke or do drugs. He will drink a beer after work, but, if that were the problem, wouldn't it happen every night? Any possible suggestions would be greatly appreciated!

I looked up GERD and the other things that those mess were for, and, he doesn't have that. These "attacks" only happen once or twice a year. It's just that this last one (Thursday night) was really bad. It's taken him 2 days to get back to normal. So, I'm pretty certain it's not any of those other things. That's why we've been so baffled. Nothing in his diet changes. Liquid or otherwise. Is there anything else it could be?