The first series called 'The Sacred Plant', about the history and use of cannabis, was extremely informative.
The second series is now airing free for the next few hours. If you hop on quick you can view the episode on pain. It might help.
Please watch it if you can. It will stop any fear you may have, and help you to inform your doctor, even if it is illegal where you are.
The information that cannabis potentiates opioids, allowing you to lower your dose, is very valuable for a start.