I don't have any personal experience with red light therapy outside of infrared in the hand therapist's office, so I went looking for any non-commercial evaluation - here is a long discussion on many promising uses: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5523874/
If you work you way through to find your kind of pain, you can probably find a direct reference or two to the actual studies.
Can you tell us a little about what type of pain you are dealing with, and what you have tried already?
Sue