Daycare causing nightmares?

My 2-year-old son has slept through the night without issues since he was 6 months old. Last month, he woke up screaming and crying hysterically 2 or 3 nights and was inconsolable for at least an hour. We figured it was nightmares and were glad it only lasted a couple of nights.

This time, he’s been up screaming and crying again for TWO WEEKS STRAIGHT! He’s also getting over a cold that turned into a sinus infection and will be done with antibiotics in a couple of days. I could chalk it up to illness, but he’s feeling much better and is fine throughout the day. He screams in terror from the second he wakes up until we go and pick him up. Luckily, he falls back asleep pretty quickly this time around. I’ve tried to let him cry for a few minutes but he ends up vomiting from the crying & coughing. I can’t help but wonder if this has anything to do with his new teacher at daycare. He switched classrooms right around the time he first started having nightmares. She’s been complaining about his behavior a lot recently, so I wonder if she’s being mean to him and that’s why the nightmares have gotten worse and more frequent lately.

Anyone else’s kid gone through something similar? Any tips, advice, thoughts? He was up FOUR TIMES last night, please help! Thank you!