Your DS EASY is exactly the same as my DD and she's just 15 months. I don't think there's a lot of developmental difference between 15 and 17 months, and you have had a lot of external factors (illness). How long ago was the smoke detector incident? It doesn't seem like that should have such lasting consequences, but I'm curious if there's something else about it.
I think the 5 hr A time is good, but I wonder if the quiet time should be counted as A time. With DD, I count her quiet time because even if she's lying down and playing quietly, she's still awake. And she's ready to go back to sleep at the 5 hr mark from actual wakeup, not from the time I go get her. I think you might want to get him back to a 5hr schedule.
If your LO is getting so upset in the crib going to bed that he's vomiting, you need to do whatever it takes to prevent getting to that point. Even if one of you goes to sleep on the floor in there a few days. The cold he's getting will prevent him from going to sleep, even if he's tired...DD had a sore throat and I didn't know it. She had trouble sleeping, and she had a day where she just wasn't "right". She kept running into stuff, whining, etc. Took her to the pediatrician, who looked at her ears, nose, and throat and told me the drainage was making her throat really red and it was probably very sore. A couple days of children's Tylenol solved that problem and she slept very well.