When should I start freaking out?

Alexah • I'm a 24 year old first time mom 💫 My son was born 3/28/17 💙
My little guy is 4 weeks old & up until now he would poop after each feeding. He hasn't pooped in over 24 hours and I'm starting to become worried. He's passing a lot of gas though. Could it be something I'm eating? I had coldstone yesterday...maybe that's it?