sleep issues

I am having a hard time with Jax .He goes to sleep fine but wakes up every 15 minutes crying.I pick him up and he goes right back to sleep.We moved his crib in our room thinking him being closer to us he would sleep all night.At first this worked but not no more.Michael has put him in bed with us and he does fine.I don't want to start that habit.We have Landen in our bed already because he wont sleep in his own.Jaxson sleeps wonderful if he is being held.This is not working ..I am going to try some melatonin on him and see if that helps.Any ideas?I could use some help with this one.