How would pain be measured in a world in which time does not exist?

Answer 1

The same way it is measured now. Patients are asked to rate pain on a scale. It is a subjective rating and is not bound to time. It tells a practitioner about the subjects personal experience. We all experience pain differently. The practitioner will treat the patient based on a subjective rating by the patient.

There is no objective measurement of pain.
The issue you raise of time, is just a hypnotic to throw us off the track.

Answer 2

Life is only possible with time. Time is the energy of everything. Without time there cannot be a world.