If you think it is nerves then Feliway plug-in or spray may help calm him.

Ripley has always had that problem but I can mostly pinpoint why. He either has a hairball (Lax'Aire the vet gave me works great for that), he eats too fast or he had some dairy. I learned that even one lick of ice cream or any kind of dairy will come right back up on him. My vet said he's just one of those cats with a very sensitive tummy.

Does Brodie's stomach seem extended or hard? Back this spring I had to take Rumor to the vet bacause she threw up a couple of times, her stomach was getting very hard and extended and she was having problems with "cling- ons" or "dingleberries" if you know what I mean. It was a hairball stuck in her intestines and the Lax'Aire did the trick.