I used to be addicted to cannabis. I smoked so much that when I quit I went through a genuine withdrawal. I had to stay at my parents house and told them I had the flu because I had a high temperature but felt really cold and shivery.
I think indica strains have more potential in people with ME than sativa. Indica plants are short and squat with broader leaves, whereas sativa are tall skinny things. Indica plants are more heavy in CBD, which is the compound that makes you feel mellow. Sativa, on the other hand, are high in THC which is the compound that gives you a giggly high.
Obviously one of the problems with cannabis is how you consume it. Smoking has its clear risk factors, not least because it costs a hell of a lot to smoke a joint without any tobacco in, so it is easy to become addicted to the tobacco. Moreover the smoke itself even without tobacco can be carcinogenic.
Brownies are one option, though they have a fairly short shelf life. Another option is to make cannabis butter which you can then add to food or spread on toast (the active compounds are fat soluble). The best option for homemade medicinal cannabis in my view is a tincture. You can dissolve cannabis in a 100% alcohol solution and then measure it out of a dropper bottle. This seems to me to be the easiest way to use it.
My dad knew a guy who had a friend with very severe ME. They sparked up a spliff one day and felt enormously better almost immediately. He went from completely bedridden to being able to help look after his kids, just so long as he kept on smoking. As soon as he stopped he would have a relapse. My understanding is the cannabis has some immunosuppressive qualities, so I wonder if that may be the reason behind his improvement.
Anyway, I won't be trying cannabis because of my previous addiction. By the end I was horrendously paranoid all the time but still a slave to it. We have good epidemiological evidence that there is an association between cannabis consumption and increased risk of schizophrenia too. The risk is probably reduced in older people, as psychosis is a young person's game.