Five month sleep regression? Or something else?

My little guy is 5.5 months old. He had been pretty consistently sleeping 7-5 since just before turning 5 months. However, in the last week he has started waking every 2-3 hours. Previously, if he had a MOT wake up, I could give him a paci or rock him for a bit and he would go back to sleep. This is no longer the case and he screams until he gets fed.

He has also been much harder to put down in general. This primarily affects night time but somewhat affects naps. The first two days of this I didn’t think I would ever be able to get him back to sleep on his own again. This included after night time feeds. These last 2-3 days he has been easier to put to sleep and has gone back to sleep after night time feeds almost immediately.

I’m really struggling with the lack of sleep. I feel like I’m in newborn phase again. I don’t really think he had much of a four month regression. Is that what this is? Just hitting him later than others? If so, how long do I just suffer through this? Could it be something else he’s working through? I don’t really see evidence of teething. He did twice in the last three weeks.

I’m so tired