HI there,
Is there any kind of routine that you would usually follow for nap time and bedtime? Maybe you swayed from it a little. Kids do really well with repetition, so I would go back to doing things you would normally do. Sounds like a temporary hiccup. It may take a few weeks, but he will get back there again. Changes can really screw a kid up, but as soon as it becomes a regular part of life, things will get back to normal.
I wouldn't stay in his room just because he wants you too, that's to much of a change from the norm. Most kids take a mile when you give an inch, so go back to tucking him in and leaving his room. Go back to the way you were doing things just a few days ago, even if he screams for you.
good luck!