Please help!!

My son is almost 2 weeks and he will not sleep through the night. He naps so hard during the day where I can barely wake him up to eat but once it’s time to go to bed he sleeps for maybe 15 minutes then starts crying. He’s fed and has a clean diaper. My doctors says he has his days and nights mixed up but how do you keep a newborn up during the day so he’ll sleep at night. I know he needs to eat every 3 hours or so and I’m doing that, making sure he’s clean put him down and he’ll be content for 15 minutes then start crying. Any pointers to get his days and nights on track??!