Preemie, 5 days no poop

Pa-share naman pls ng experience nyo Momshies!!! My preemie is 1month 25 days (actual age) now. Last week 3 days sya di nagpoop, dr gave him glycerin. Nakapoop sya, madami. And now, 5 days n wala p din but he keeps on straining. Ganon sya 2 weeks ago pa, namumula p s pagstretch. Malambot naman tummy nya at ok ang feeding. Similac po milk nya. Pls po pa-share naman ng experiences nyo...