My LO is 3 weeks, 4 on Sunday and as of today he's had a mucousy stuffy nose, is choking on his…

My LO is 3 weeks, 4 on Sunday and as of today he's had a mucousy stuffy nose, is choking on his milk, spitting up a lot, very fussy, won't sleep, and I noticed a little bit of green mucous in his spit up... Any idea what could be going on or what I can do?? No fever as of right now