Is my baby constipated and how to get relief!

Brandi Lynne • Mommy to Lila May 3/1/15 ♡ & Vera Rose 9/28/17 ♡
Hey ladies I need your advice! Our Lila is 3 weeks old now and typically eats every 2-3 hours. But she hasn't eaten since this morning and hasn't had a bowel movement since last night. She ate a lot yesterday and now all she wants to do is sleep on Mommys chest. We called the dr but she said it's normal for a 3 week old to not poop for days. But I feel like it's not normal to go hours upon hours without eating. Have any other mommies experienced this and how did your little one get relief?