Feeding Troubles 6 weeks old!

My little guy was born 6 pounds 11 ounces and from day one had a horrible time eating. He lost a little bit of weight and would only drink a ounce at a time every hour until he was 3 weeks old! At 3 weeks old he started drinking more and more each feeding and going longer periods without eating. Well for the past 3 days my son has started eating 2 ounces every 2 hours and is sometimes fussy while eating. I’m at the end of my rope trying to figure out what to do. Any advice?