My child doesn't want to sleep in his own bed anymore?

My son is 17 months old, he was sleeping in his own bed from 8 months. We would put him to bed with a bottle and his pacifier in the one hand. He would finish his bottle and put in his pacifier himself and sleep for 11 hours without waking up. About 3 weeks ago he started waking up 5 times or more during the night screaming. He doesn't want to fall asleep by himself anymore. I have to lay with him till he falls asleep, but there after he keeps waking up screaming if i'm not there with him. What could be the cause of this.