I have an interesting 'theory' i guess you'd call it, but it's pretty obvious. Being a methadone/opiate addict, I found myself strangely addicted to marijuana. Clearly I know the difference between a physical and 'mental addiction', which i always considered as bullshit as I never had a problem or withdrawal symptom after months of use of every mentally addictive substance. But marijuana I hate to say it, can be extremely addictive if you're already an addict. I was smoking 2 - 6g daily strictly through bong which isn't even THAT much, but the irritability was still the most prominent 'withdrawal' symptom. However, also being a smoker/nicotine addict, the irritability + opiate rage of not being baked was sometimes overwhelming. Other than that, it was pretty standard. Couldn't eat or sleep unless stoned. However the main difference I noticed now being a stoner junkie vs. just a stoner, is that I was also very nauseous with vomitting, body temperature wasn't regulating with goose bumps, and other things evident of opiate wd, though I was on my methadone so I knew it was the bud.
Basically, the cannabis 'withdrawal' greatly exasperated feeling shitty from other addictions.