My sil has some questions about her 12 week old and I told her I would ask the "pros." Her ds wakes up after every nap after only 45 minutes and is extremely grumpy after he wakes up. He can't soothe himself back to sleep and is grumpy until the next naptime. She has let him cry but he works himself up so much that he can't go back to sleep. Any tips? Thanks!!!

He's a bit young to soothe himself back to sleep. Is he maybe not getting enough to eat? Is his nap interrupted by noise? Sorry I'm not much help.

yeeeaaah at 12 weeks..it's all about eat/poop/sleep/repeat
I wonder if he's not getting enough to eat before being laid down to nap. In any case, I'd just pick him up and nurse again. :)
Maybe try wearing him.

Ditto to everything Tara said.

And if not- is he gassy? Does he need to burp? Does he seem uncomfortable? Hot/cold?

Just gotta go down the list with these wee ones.....definitely too little to just let him work it out on his own.

Thanks for your help! I will pass the info on...