Need advice! TIA!

I need advice!

My baby girl is going on 6 weeks old, she’s tiny! And she’s getting congested... she’s breastfed and supplemented with formula... she’s wanting to nurse and be on me a lot more then usual. She usually likes a bottle but she’s not really taking to them right now.... she has her 1 month dr appt tomorrow so I’m definitely going to be asking but I was wondering if there’s anything I could do for her now?

Her cousin came over and was really fussy and even worse congested, he is 6 months old and has been congested for the last 3 months... so idk if he passed her something or what.... and his dr hasn’t done anything to help him.

I have a humidifier going and an oil diffuser with eucalyptus oil mixed with the water.... it doesn’t help that our weather is awful and has changed drastically in a short time frame.

I feel like I’m getting a scratchy throat.. I’ve been taking elderberry and vitamin c to help knock this out...

Is there anything that can be Done right now?