15mo sleeping badly-separation anxiety?

[MatchsticksForMyEyes]

I have sleep trained him a few times and he has always regressed. I have managed to completely knock off night feeds and he is STILL waking.
I can settle him by laying him back down and patting him, but then he will wake up at 15 min intervals. I have a 3.9 DD and am working p/t so can't do that all night.
The only thing that now works is if I put him in bed with me, cuddle and shush him and he does sleep straight away. So he obviously isn't waking through hunger.
Do I just go with it and co-sleep or keep persisting with trying to get him to stay in his cot, which is exhausting for both of us.
I just want a full night's sleep!

me too! my lo is almost 16 months and we co sleep and its a nightmare!!! i think i get even less sleep now than when he was born.we are in the middle of sleep training its going well he needs a little help getting settled but falls asleep on his own. dh works til 2:30 during the wk and he doesnt get much sleep either. im going to start work in a few wks and we are moving house nxt month to a 2 bedroom im hoping this will help our situation.

I'd cosleep for a bit and then try again after a week or so by staying in his room - can you set up a bed or something? Could he be teething? The molars are pretty nasty!