Sleep regression or teething or nightmares

My son has been a champion sleeper since he was about 1 year and a few months. Now this week he’s waking up around 5 am screaming. No temperature just really inconsolable. He wakes everyone up early and he won’t be soothed back to sleep. One time I’ve held his hand to see if he would go back to sleep but he just played with my hand. So now I’ll go in and try to sooth him and he desperately want me to hold him like he’s scared. He takes 2 hours naps and they haven’t changed any. I know he’s working on his bottom 2 canines but he’s never done this early wake up thing for his other teething 🤷‍♀️. Any guesses?