Weird and embaressing panic attack thing? What exactly is it? How do I stop it?

About 3 or 4 times a year, whenever I'm really tired, stressed, or experiencing prolonged anxiety, I will start dazing in and out, freaking out and literally panicing over something harmless like a commercial, and say random things almost as if I'm in a deep dream, but I act it out in real life. I rarely remember most of it, I just remember it happen. It also happens a lot when I'm sick or feverish. I will sweat, pace, convince myself I will die for reasons unbearingly fictional, and see objects that arent there. Also thinking about widths of things like pencils or my wrist will terrify me. What is happening to me? My parents called it night terrors when I was younger, now I'm 15. I've also had a pretty awful childhood due to deaths in the family if that helps.