Son constipated

JoAnn • Mom Of 2 Handsome Princes 11.17.04 && 2.26.15 😍😍
My son was born on Thursday 2.26 an since last night he wakes out of a deep sleep screaming crying as if he's been hurt just to pass his tiny poop. I just thought he had an upset stomach but it's now 7a an I just changed his diaper an it looks like little nuts inside in poop still (this is diaper #3 since around 10p) an I can tell he's in pain when it passes an I feel horrible is it okay to give him stool softener an could it be the mixture of soy formula an breast milk I've been doing only cause I'm not sure if he is getting enough breast milk or could my milk be the reason behind his constipation?