Baby not getting milk

So my son is two weeks old and is strictly breastfeeding. He’s done extremely well with it. Went from feeding every hour to hitting a growth spurt and doing every 30 mins. And after he’s done he always has a little left on his chin. Well today all day long I don’t think he’s gotten any milk at all from me. He normally makes a sound while he’s drinking and he hasn’t at all today. No milk left on his chin, and after I take him off he acts like he is starving. So I don’t think he’s getting any at All and I’m not sure why. He’s latched on good just doesn’t seem to be getting anything. So I had some already pumped and gave him that and he makes his little noises and everything so I really don’t think he’s getting anything from me.