Hi Frank,
I'm not sure about hiccups, never experienced that with Rex. It could be a respiratory infection, but I would only be guessing. Three hiccups a minute does not sound good to me. Why don't you PM Tracie(drache613). She could help you out.
If Stewart seems distressed at all, I would take him to the vet.
I hope by the time you get this reply he is better.
Good Luck!
Dawn