I was supposed to start my new job on Monday, today I get an email that my drug test (taken 2 weeks ago) is needing further testing, and my start date was pushed back

To be clear I have prescriptions for a benzo and amphetamine for several health issues. I’ve never had a job push a start date back over this. I never even heard from the lab for my prescriptions which I noted when I took the test… Im absolutely horrified. Why wouldn’t they even call me for my scripts and instead go to my employer to push back my start date? This is in Pennsylvania, never worked in a state like this before.