I've suffered with panic attacks since the age of 15, so have had them for over 40yrs.
I can still remember the first one I had like it was yesterday and it scared the crap out of me.
I would recommend going to see your GP too, just so that he can rule out anything else. There are a few physical conditions that can cause symptoms of a panic attack, none of them are serious but I think it's always good to have any possible physical conditions ruled out.
Panic attacks always run a set course and they will always burn themselves out. They are caused by a surge of adrenalin and what keeps a panic attack going is what they call "second fear". When we get a panic attack we get that "omg" feeling and think it's never going to go away so we add more fear and that just keeps on feeding the initial panic.
There are a number of ways to reduce the intensity. A lot of people I know sip iced water or even pop an ice cube into their mouth or bite on a slice of lemon, apparently all these things can work. I think the paper bag has already been mentioned, but you can also do this just by cupping your hands over your nose and mouth. Also learning to breath properly from the diaphragm is really helpful as most people with PD tend to shallow breathe and that makes the symptoms worse.
Panicure is a good site that explains all the symtpoms and suggests ways of coping with them
There is also a forum called No More Panic and also No Panic who have a telephone help line service.