My baby won’t let me put her down! 😩

Hi guys! So I have two daughters, 3 y/o and a 5 week old and it’s been rough! Things are starting to get better though and we are getting into our groove slowly but surely. EXCEPT my newborn will not let me put her down for more than a few minutes at a time when she’s awake!! This is all day during every wake time. I am trying to remember if my first daughter needed to be held this much but it was all such a blur. Doctor also thinks she has reflux so we just started Zantac a few days ago. It’s seemed to help a little at times but overall it’s pretty much the same. I can’t get anything done and my arms are killing me!! Is this normal?! Any suggestions would be great too! Thanks!