PLEASE HELP!

Idk what to do every night for weeks now my son and sometimes daughter will wake up screaming and crying multiple times a night. It’s getting to the point that I’m yelling at them to go back to sleep!. I really don’t know why it has started all of a sudden, they have been in their own room for months now. They don’t watch anything scary; they have a night light, and they know we are right outside but still my son mostly will wake up screaming and crying for his dad! I can’t handle it anymore.

Edit to mention they are 5 and 2.5