Can a panic attack just randomly happen for no reason?

Out of the blue: That is the common way panic attacks manifest.

Yes: Panic attacks often come out of the blue. You may want to try relaxation breathing. If you want to avoid medication for your panic attacks, i highly revommend the book: the relaxation response by benson. Read the entire book, then start doing the exercises as contained in the book. Start with 5 minutes twice a day working up to 10 minutes twice a day. You can learn to relax instantly, anytime.