Is my newborn okay? Poop related

[ajja2021]

Hi,

18 day old DS was switched from combination feeding (breast milk via bottle and formula via bottle) at 13 days old. Initially he was okay but then became constipated for the last 3 days, today has been very uncomfortable and straining. He can't seem to lie flat without crying after a couple of minutes, he's had 6 large poo's of a yellow/green colour and mostly watery or loose consistency.

He's so uncomfortable and he's also projectile vomited twice today

He's 9lb 6oz and is on 4oz on demand which is usually 3-4 ounces.

Is this normal? Older DS was exclusively breastfed so I've never had this issue, I hate seeing him so pained and stressed he's been such a content baby until now

Can anyone help?

Which formula is he on OP?

SMA

Watery, loose stool plus projectile vomiting are symptoms I’d get checked out at that young age. I’m sure he’s fine, but better safe than sorry. Poor baby - and poor you!

Has the ratio of the breast v formula stayed the same?

I know this is a really rude question to ask but is the formula being made up properly?

My kids dad had a habit of putting an extra scoop in as he thought it was better.
My stepmum used to put a scoop less in, which made my daughter puke it up.

I agree that you should be seeking help immediately, it doesn't take long to mess up a babies digestion but vomiting can be serious (milk being chucked back out because it was made wrong is easily solved but a check is needed)

This sounds like a dairy allergy to me, I’d definitely check with the doctor