I'm no expert, but it is my understanding that Klonopin has a rather short half-life, so I don't believe it is something that would build up and stay in your system for a long time like other drugs such as Prozac, etc. This could be a good thing if you need to take Klonopin on occasion just to take the edge off so you can have a relaxing dive. Many people with anxiety are completely calm and relaxed when diving anyway, but driving can bring on sudden events like yours if you are already stressed out about other things in your life, if you had a bad day, etc. If something goes wrong during a dive, then that could cause an onset of panic, which could be very bad for someone who is already susceptible to panic, so you need to be aware of your mental status before and during a dive.
Like others have said, I would get a thorough check-up first, but I would not be afraid to try Klonopin, or even a weak dose if the side effects are minimal. You can try it at home for a while, and if the side effects are not severe and you can handle it, then you could try weak doses on dives (or even drives) if you are becoming susceptible to panic attacks.
On a personal note, driving can be unnerving for me at times, depending on traffic and how my day is going, but I am always relaxed and "in my element" when diving. It is also important to recognize anxiety vs. outright panic so you will know how to handle your own situation.
In our crazy, competitive, unpredictable and fast-paced society, there is a lot of undiagnosed anxiety and panic going on out there that people keep "in the closet." People should not expect to be able to stay on top of life's pressures all of the time, and they should not be ashamed if they have some type of either chronic or acute anxiety or panic issues. The most important thing is to recognize it, and then do something about it.
Hope this helps.
