Mummy's I need advice. My little one is 24 days old now, (how time flies!) and she has been so fussy for a couple days…

Mummy's I need advice. My little one is 24 days old now, (how time flies!) and she has been so fussy for a couple days now & seems to have a bit of a cold, she has a snotty nose & occasional cough. She is not sleeping at all! And seems to have less wet nappies. I'm exclusively breast feeding so don't know exactly how much she's getting but I have a good milk supply & she's been gaining weight nicely. She seems like she's got a tummy ache? What can I do to help her settle? I haven't slept in days!