Night terrors

Hi

I've got a 15 month old son who normally sleeps through the night baring maybe a few occasions where he wakes up, mumbles, finds his dummy and goes back to sleep.

Recently there have been episodes normally been 0000-0100 where he wakes up, stands up and screams and crys and shakes. He is almost instantly calm if you pick him up but even when you rock him back to sleep or lay him down he instantly starts or at least starts within 5/10 min again.

I've tried anywhere between 1 hour and 3 hours trying to get him to settle down before exhaustion gets me and I take him and his sleepyhead pod in beside me. If I lie against the pod and give him a cuddle he'll settle back to sleep. 

I'm 32 pregnant with my second and know I've got more sleep time challenges ahead so need help asap.

Has anyone else had this before and know any tips for dealing.