3 week old only sleeps when being held . Ftm seeking advice !

Nadia • Miami ,FL
I'm having the hardest time getting my 3 week old to sleep in his crib. He only really sleeps in my arms or on my chest . When I put him down , he is up within 20 min . 
Overall he sleeps better during the day and been trying to slowly get him to learn the difference between day and night by keeping the room dark at night and bright during the day . 
Nothing seems to work.ive been struggling with breastfeeding to a point of tears with every feeding and adding that to endless night of him in my arms I'm really struggling . 
Any advice , pointers or suggestion would be greatly appreciated!!