Kelby,
There are loads of really good web site about anxiety - read them.
You can find ways to teach your son to control his anxiety, without the use of meds too!

Basically. ask yourself the question, do youw ant to get to the bottome of it? if so go to a coucellor and see what is making him worry. However, finding out the reason NEVER stops the attacks, you still need to learn how to deal with them. The techniques are basically learning to recongnise when an attack is starting before it gets too bad, and learning to breathe properly and ofter to challenge the thoughts that you are scared with more logical thoughts such as " i am safe and secure, anxiety cannot hurt me"
You can spend thousand trying to find out why and often there maybe a underlying cause to the anxiety but you must learn how to deal with it, most often though there is no cause to the anxiety other than how your body is constructed and you are just prone to them. Learning to cope is a must, digging into the "reasons" is only useful if you feel there is a strong issue to blame, like abuse or bullying and so on, but usually if there is nothing big that seems to be causeing it, the pychiatrict option becomes little more than an interesting aside but does very little to help the person recover. The only way to get over the attack is to learn with cognitive behaviour how to control them. So by all means, g spend your money on trying to find out the "whys" of anxiety, but the most important thing is to spend time learnign to cope with them. Check out this link too, especially if you are in UK, but go anyhow, they can help you.
http://www.firsteps.demon.co.uk

Best of luck, but do use your own initiative, has he always been a nervous person? is he okay at school? any thing changed? why does he think it is happening? get him to tell you all about how they come on and how they feel, as you learn more about anxiety you will see if they follow a pattern. anxiety attacks always seem to produce the same basic symptoms in most people who suffer,
any of the following are common.
headaches.
stiff neck.
Nausea.
feeling unreal, strange or weird.
feeling faint or dizzy.
feeling hot, breathless.
mainly feeling terrified that you will die or lose control. having unwanted and unpleasant thoughts that you can't stop thinking.
those are jsut the main ones!
but check out the web, there is lots of good info. Unfortunately the medical proffesion is not that good on the whole at understanding anxiety disorders, unless you are very lucky, you will have to do most of the work yourself, so get educated on it!
Peace
Hazza