I need some direction and hope you can help

My in-laws live in Houston and SO and I live out of the country. We just received father-in-law's call saying that he have COVID symptoms. My SO is trying to figure out what to do (running around like a headless chicken), and I'm trying to bring calm back home while being proactive. Do any of you know of a location that can do tests close to 610 and 45 and it's open tomorrow?

I've seen that some sites require previous appointment or an email for registration. It's frustrating not being able to be there, nor having any other contacts near them to help. I'm not sure how is Houston testing and how accesible is, hence why I came here for guidance. Hope you can help.