My five day old isin't eating enough?

So I had a baby five days ago. And he was 9lbs 11 oz so he was a big fella. He used to eat a lot. If i didn't feed him evrey two hours he got MAD. Now I have to wake him for evrey feeding and it takes a while for him to even eat 2 oz. He seems sleepier too. I only got about 2 hours of awak time today the rest of the time he's been sleeping. I had his first appointment and the doctor said that he didn't look jaundice but he didn't test him. I just wonder why he's so sleepy and why his feeding habbits have changed. Could he be jaundice? can I wait until the morning to call? I'm a FTM and FREAKING out. Please help?