18 month sleep regression

Help!!! Are any of your babies going through their 18 month sleep regression?! From what I've read online it's one of the worst and said it could last from 2-6 weeks. My son, who has been a great sleeper from early on, has been waking in the night around 2:30 until 5:30. He screams and hits and wiggles and won't relax. Nothing in his routine has changed, he doesn't seem to be teething and he isn't sick. I have been trying to soothe him back to sleep and follow the same sleep training steps that we did when he was a few months old but nothing seems to be helping . Any thoughts or tips??