Think my son is constipated

He hasn’t had a poop since yesterday and when he did he was trying really hard to squeeze one out. Then he finally did and it was like a little hard ball, then again another hard ball maybe 10-15 minutes later. Then after that it was a big sloppy poop. He hasn’t pooped today but he’s been really fussy and crying a lot whilst he’s awake, and sometimes seems like he’s trying to squeeze another one out.

Also he won’t drink most of his bottle and I’m wondering if this is because he needs to poop but can’t 🤔

I think he’s constipated and it’s annoying or upsetting him. How can I help with this?