Sudden nighttime separation anxiety

Hey mamas! So my little guy seems to be having some separation anxiety at nighttime and I’m not sure what to do about it as everything I have tried so far has failed.

For a background- the way I normally put my son to sleep is to lay in bed with him until he falls asleep. I used to rock him to sleep all the way up until about 4 months ago 😬 but I decided it was time for him to be a little more independent at bedtime. Laying with him actually went really well and we had no problems until about 2 weeks ago. Normally if he woke up a little during the night he would settle himself back to sleep no problem, but here recently that hasn’t been the case. He has been screaming once he wakes up and realizes I’m not in there and getting out of bed to come find me which he has never done before. The other night he even opened his bedroom door, so I had to put a child lock on his door since he can also open the gate at the top of the stairs.

I have tried getting him to sleep with his favorite stuffed animal for comfort but he has never been one to want anything in his bed with him (except me 😅). And just recently I have been working on sitting next to his bed rather than laying in his bed with him in hopes he gets more used to falling asleep on his own, but I feel like that is making his anxiety worse.

When he wakes at night and I go in to comfort him he keeps his hand on me no matter what- but he prefers to lay on me. He will wake up several times just to make sure I’m still there and sometimes does it so much that he keeps himself from going back to sleep. We have had many 430-530 mornings when his normal wake up time is about 745. So needless to say, neither of us are sleeping well at all and I’m at a loss as to what to try next 😵‍💫