[orthopedic surgeon, who took an X-ray and diagnosed a herniated disc, probably L5 S1. He prescribed physical therapy and instructed me to wait for a month before we explore the next step. The pain was diagnosed as sciatica. ]

It sounds like the ortho surgeon dx'd sciatica not the chiro.

Ortho probably wanted to give PT a good try before following up with MRI if no improvement from PT.