Sick baby

So my daughter is congested and has a cough.

She usually eats 4 oz every 2-3 hrs but in the past few days she’s gotten down to 1-2 oz every couple hours & she won’t take anymore than that! I try so hard to give her more but she won’t take it. I’m worried she’s gonna get dehydrated.. when I called her doc she said it wasn’t a cause for concern as long as she has more than 3 wet diapers in 24 hrs. But that just seems like such a big change! 4 oz to 1 oz ? Like come on 🤦🏻‍♀️