See your doc. After 30 years in a high-stress, emergency response career with no problems, I thought I was immune to that sort of thing. After retirement, I found, much to my disgust, that I began having occasional attacks such as you mention. Turned out there were some subconscious things going on I didn't recognize. The doc gave me some low-dose Xanax for use in those cases and it did the trick. It only took 20 or 30 minutes to take effect. Now, I never need it but back then it saved a few trips. You just learn to do some breathing/relaxation exercises until the med kicks in.

There is probably something going on in your life that is causing some low-level anxiety. On occasion, that can flare up into a full-blown panic attack for no apparent reason. See your doc.