When you submit proof of your long term disability it’s only as good as how it looks on paper. Medical records are the most important, but keeping a daily log of your pain and symptoms is further proof of your disability.
You should share your pain journal notes with your treating doctors and have them incorporated into your medical records. Your journal notes can be sent to the disability insurance company if they ever ask for further documentation. You can not exaggerate anything in your journal as you may have been under video surveillance on the same days of your journal notes.
Here is an App that could be used to track your pain and symptoms.