hungry baby maybe?!

My 4 week old son has 6oz every 3 hours! He used to finish off his 5oz bottles and cry! What's your little ones on? The longest stretch he will go is 4 hours and that's on the nights! 
Also he will wake up for a bottle at 8pm, drink the whole 6oz and then cry for more! I give him more and he is ALWAYS sick! It's like he wants more to be sick to get more after! He cries after 10 mins of being sick wanting more milk! Then he'll go bed after? Anyone elses baby like this?