I would try to find out what you can about the genetics and cannabinoid/terpene profile of Madman OG. It does not seem like a very popular strain, and if you do not grow it yourself, you may find it difficult to procure. Researching the genetics and cannabinoids/terpenes can allow you to pinpoint the right molecules that are helping you. There are many strains that will be able to help you with your pain, you will just need to find the ones that work with your body.
Unfortunately, the industry is not mature yet, so there is still some guesswork in finding the right strains (emphasis on the plural there) that help you to be the best you!