@tami3- Welcome to Mayo Connect, I'm glad that you found us. Yes, chronic pain absolutely can cause you to feel sad and depressed. I say sad because pain can really put a kibosh on experiences that you know you can't do, such as move in certain ways because you've tried them. Sometimes I feel like a pouty child when I can't do certain things because of my lung cancer.
CBD oil has been reported to help people who have pain. You need to ask your doctor because CBD oil can interfere with certain drugs. You can read all about CBD oil and pain here- It's important to read all the feedback so that you can make your own choice.

"There have been recent news stories about the potential promise of CBD and/or THC oil and fighting lung cancer, such as these news stories:
https://abcnews.go.com/Health/Healthday/story
https://metro.co.uk/2018/03/25/could-cannabis-help-cure-lung-cancer-this-man-thinks-so-and-hes-already-spent-1-5m-on-research-7266643/
However, you'll note that both articles are quick to point out that any potential positive effects have only been studied in petri dishes or on mice in a laboratory (in vitro). This is not the same as testing and discovering positive effects in humans. So far CBD/THC is still less effective than current drugs and dosages have not been tested or proven.

Here is more information about studies done so far in vitro from the National Cancer Institute: https://www.cancer.gov/about-cancer/treatment/cam/hp/cannabis-pdq (medical professional version)
https://www.cancer.gov/about-cancer/treatment/cam/patient/cannabis-pdq (patient version. See answers to questions 6 and 7)" Colleen Young

There is nothing that substantiates that CBD oil cures anything. But it does help a lot of people as you will see with all the posts.
https://connect.mayoclinic.org/discussion/using-cbd-oil-to-help-withdraw-from-serapax-benzo/
I hope that you feel better. Please let me how you make out. We are all here for you!