Toddler having hot flashes

For about a month now, maybe a couple times a week, my toddler has been having hot flashes out of nowhere. He is doing things like watching tv or playing with his toys, not over exerting himself, and then all of a sudden gets really hot, sweaty, and clingy/cranky. He has a meltdown for like 20 minutes, and then it seems like he just snaps out of it and is fine. I’ve taken his temp when this happens and it’s always normal. House temperature at 70. Has this happened with anyone else? Idk what it could be.