5 year old with croup, worried for my 10 week old

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I am SO nervous for my 10 week old. my son wasn't feeling well all day today and just now woke up to that barking seal type of cough and I know it's croup. I gave him Tylenol to ease his discomfort (had a low grade fever) but I'm terrified for my 10 week old baby catching it. Our apartment is TINY and there's no way to separate them. I just sanitized everything and anything he could've possibly touched but I'm still so worried!!! My 5 year old keeps coughing everywhere so I'm paranoid it's airborne 😩Has anyone been in a position like this? Has anyone had a baby with croup?