constipated baby?

Catrina

we've been feeding my 10day old Similac pro advanced for 7days with about 2oz of breast milk every other day. today he had hard poop for the first time. is it too early to switch to a more gentle formula?

he's not dehydrated because he pees up a storm and has been since we switched to formula.

we have a call out to the doctor, but I want to know what y'all think too.