1 month old with cold symptoms

My LO will be 6 weeks tomorrow. Yesterday afternoon she became fussy and wouldn't go to sleep unless she was on us or we we're holding her. Even then, she only slept maybe 20 minutes at a time (she normally takes 3+ 1-2 hr naps). She constantly wanted to nurse too. After her last feeding for the day she has been acting normal/not fussy but started sneezing a lot more than usual and I've heard her cough maybe 4 times. Overnight her nose has gotten stuffy and she is having more frequent poo diapers but still eating well and acting normal. Also, no fever at any point so far. Should I be concerned?? HELP!