How do I know if it’s more serious than a common cold/cough?


Basically my question is how do I know if it’s RSV. It’s day two of my daughter having a runny nose, cough, and low grade fever. She is in good spirits but definitely sick. We took her to pediatric urgent care and they said RSV doesn’t develop until around days 3-4. How do I know if it’s RSV or just a common cold/cough that needs to pass?