@Bridget what kind of sleep song? I am experiencing this as well. I have to lay with my LO at night. During the day, naps only last 5 minutes and it doesn't matter if I'm holding her.
You probably already do this but slowly putting baby down butt first and putting light pressure on their chest for a few seconds helps with their startle reflex. Also white noise and a dark, calm environment. My LO got more sensitive to her sleep space at that age as she was more switched on. Now we try and layer the same sleep associations for day and night sleep so she knows it’s time for sleep - we do white noise, red light, the same 3 songs at the start of every sleep, and a swaddle bag. Don’t worry about falling asleep independently - that’s too big a skill for most babies this age. If transitioning from your arms is the issue you could put baby down and help them to sleep without picking up using shushing, butt pats etc but it only works on some babies - I know my girl would be having none of it and needs bouncing and shushing in my arms.
I’m so sorry! I just went through something similar with my LO at the beginning of the month. I ended up following the guidance from the book Sweet Sleep from Le Leche group to safely co-sleep. It was the only way both her and I could get some rest. I also pair music with her falling asleep so when she hears any of the 3 “sleep” songs she gets tired and it’s easier to rock her back to sleep and keep her asleep. Once she’s down and asleep I can turn off the music. It only lasted about a week and we were able to get back to her sleep schedule! Hopefully this is just a phase and he’ll be back to letting you get some sleep soon!