I think FATE speaks some very words here OP.
You might be about to hit the 4 month sleep regression too, which can be hard work.
We sleep trained at 4 months and it served us well. We based our actions on PUPD but didn't actually pick him up as it just made him cross to be put back down.
My DS was in a routine of feeding to sleep. I didn't like that every time he woke, I had to feed him. I would have been fine if it were every few hours but it was every 45 minutes! He didn't need the milk, he wanted the comfort.
So my DH and I accepted we needed to work together to change the situation. For the first week, he would be fed to sleep at bedtime by me, but the DH would cuddle him. When he'd stir he'd know straight away as he was still holding him so he could shush and pat him back to sleep. DS wasn't keen at first but he was always held and comforted so there was nothing wrong with it. We agreed that if he woke an over an hour and a half after a feed he could be fed back to sleep, but anything before we'd shush and pat him.
Then over the course of the next 2/3 weeks we moved DS further away from 'us'. So instead of being held he was snuggled up next to us, then next to us but not touching, and then finally in the bedside cot. After a few weeks he could generally be resettled in the night with just a few shushes and pats whilst he was in his cot.
From then on he improved on his own, I think because he didn't feel worried or alone in his cot. It was a safe place for him, mummy and daddy were there if he needed them. He started being able to settle himself as it was enough to know we were there or even just for us to lay a hand next to him to hold.
By the time he moved into his own room he was able to settle himself to sleep again if he woke up at night. It was a little while (10 months) until he could get himself off to sleep alone, but we were able to cuddle him to sleep easily and then pop him in his cot. He'd wake up a tad but was happy in his cot so would just closed his eyes and go back to sleep.
HTH
Good luck