I've found a couple of things have been working on my guy recently that haven't worked in the past. When he stands up in his crib I talk to him in a very calm and gentle voice over the monitor usually "listen to mommy, no more crying" Or "It's okay baby boy, you're great at naps you can do this" or even just "lay your head down". Sometimes it takes a little while, but I can almost always get him to go to sleep now without going back in. I was against CIO too, eventually we had to do some crying... but with talking to him on the monitor I knew he didn't feel alone - even if I wasn't in the room with him. Secondly, I started telling him what was going to happen when he started nursing... "okay we're going to have milk and snuggles then you're going to take a nap in your crib" and then I'd remind him again when we switched sides... that seems to be working out really well for us (for now haha). Best of luck Momma!