1 week old baby: upset tummy

R • 35 years old 💍 Married 2015. 👶🏼💙 Oct2016 👶🏼💙 Nov2019
Hi, before I call my midwife can anyone suggest anything...
My baby is 9 days old and since yesterday evening has been showing signs of an upset tummy. Pulling his legs up, tensing, crying with strained face. I've tried gently rubbing his tummy to try and help with any gas. He's been passing wind but no poos in about 16 hours. Still having wet nappies though. He seems most comfortable laid on his tummy on my chest. 
I've tried feeding him slower, breaking more for burping etc, he never seems full but I'm worried if I feed him too much he'll have more of an upset tummy. He is also bringing up more milk than usual after feeding. 
Any help/advice please?