I Have Occasional Bouts When It Feels Like My Core

I have occasional bouts when it feels like my core temp rises, I feel nauseous, lightheaded, weak & my chest feels tight. I try deep breaths and cool liquids to mitigate but once it starts I generally have to ride it out. Maybe twice a year for past 15 years. Yesterday, I actually vomited and passed out. First time for that. CT & EKG good. Used to think it was vertigo related. No thyroid issues or diabetes. Am overweight. No one seems to have any idea.