nightmares at 2?

My son has been waking up from Naps and in the morning screaming and won't let me hold or come near him. Yesterday it lasted almost 20 minutes after he was up. It’s concerning to see my son distraught, inconsolable, hyperventilating. For some background he goes between my and his Dad's house (Friday night to Sunday). He kept saying, “bye Mom, see you, got to go while hysterically crying. So tonight he’s at his Dad's, I explained and showed him a video of it. Basically, he thinks I’m nuts and it’s nothing. I’m sad leaving him, especially right now. I hate leaving him like this. It’s hard.