5 year old having nightmares

The past few days my son has been waking up drenched in sweat, screaming, and panicking. When I get into his room, he looks like he’s awake but he’s talking nonsense. I’m assuming he still thinks he’s dreaming at that point. He is absolutely terrified and it has me really worried.

The only thing new in his life is kindergarten. It just started last week. When I tried to search online I saw that kids have nightmares around this age and starting school can trigger it. He didn’t go to preschool, so this is a huge change.

Has anyone else gone through this? Does it last long?