Oh gosh, do not let him cry it out! He is now getting traumatized and panic stricken!
He is also at the age, where he has "separation anxiety" and he needs you.
Imagine... if you were sick or had an emotional trauma/problem.... and your husband told you to cry it out without him and don't come to him for help or hugs or comfort... and told you to just stay in the bedroom and sleep it off and fall asleep because he is tired of hearing you whine and cry about your problems AND that he would NOT keep you company or sleep with you until you stopped it, and he told you that you are just 'manipulating' him on purpose and he will not be trained that way as a Husband? How would YOU feel if your husband told you that whenever you needed him?
I don't mean to be sarcastic... but imagine how your baby feels. DO NOT let him cry it out... he is very panicked about it all... and then, sleep WILL become a HATED time of day for him... you do NOT want him to "learn" that. Sleep and going to sleep, should be just as pleasant as any other time of day. Kids LEARN THAT from, us.
It does not have to be a "battle" or a trauma.
Also, be mindful of the developmental changes they go through, in tandem with the developmental "needs" they have emotionally and mentally... which they need us to help them through it.
It takes routine, and consistency to build up a good pleasant pre-bed and pre-nap routine. Keep it soothing, quiet, and not hyper. Allow him to wind-down before bedtime or nap time first. For me, it takes me about 1/2 hour to get my kids wound-down first, BEFORE bed/nap, THEN they go to bed/nap. Its all about "TRANSITIONING" the child, cuing them as to what is coming up, letting them know verbally "bed time soon, lets get ready..." then doing it together.... and not rushing them.
All the best, I know this is not easy, but it is just one of MANY hardships for the child, and a learning experience for us parents as to how we can help our kids.
Bear in mind, that at each stage of development, sleep quirks DO happen... sleep patterns are not static... but WE can help them have good sleep "habits" by being consistent in a comforting way, instead of battling with them about it.
Take care,
Susan