Thanks.. the hard thing is that they come on all of a sudden
Yeah, they can do. Is there something else in your life that you're finding stressful?
Water tends to, at least, delay mine until a more convenient and less embarrassing time.
I used to get them a lot.. it's all about recognising when one's coming on and taking some deep breaths, sitting down, and calming yourself down. Believe it or not, you CAN control them. Just think, 'wtf, I can stop this' Or if you're mid-panic attack, distracting yourself always helps. Look at stuff around the room, do some maths, just think about something else instead of freaking out.
Edit: Also think about what's making you have them. Are there any underlying issues that's troubling you? If there are, sort them out, the panic attacks should start to subside then.