Yeah, question, why are we on the fourth floor?
I asked her mother, but we both or weren't sure yet
This is where the doctor said that we should go

from Chino XL – Father's Day Lyrics on Rap Genius

Meaning

After noticing something during an appointment, the doctor sent them to have their daughter tested for cancer. One floor of the hospital is usually used for a few health issues.
For example:

In this particular hospital, the place they run cancer tests happens to be on the fourth floor.

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