When you have a script which should only accept input from specific pages how do you control this?

I would never make such a script, because the premisis is flawed. HTTP was created as a stateless protocol, and that's how it works best. Why would a resource care which resource the user consulted before? Why try to funnel the user through a virtual corridor? HTTP wasn't designed for that, and any trick you try will eventually fail. As you found out.

Don't fight the system, work with it.

Abigail