My primary care physician sent me to a special spine clinic to help sort out what is causing my chronic (severe) low back pain. I had to fill out three different questionnaires about what I can and can't do. And there were two separate papers on pain intensity. Why are they asking me all these questions? Pain is pain. If I say it hurts like hell, why don't they believe me?
Pain is a subjective sensation. It can't be seen, photographed, or shown to someone in three-dimensions (3-D). That can create a dilemma when trying to measure this symptom to show improvement with treatment.
What you were doing with all the questions was establishing a baseline for your symptoms. In other words, creating a description of the frequency, intensity, and duration of your pain on a daily basis and with various activities. You will likely have to fill some or all of these forms out again later to see if there have been any measurable changes in your pain.
If you are not improving with the prescribed treatment plan, then it might be time to look for a different treatment approach. If you are improving, then the before and after measurements will help show by how much. It's easy to start feeling better, get used to the new (improved) level of pain but still not be pain free. The result can be the patient's perception is that there's been no improvement when indeed there has been!