Coping

As I’m looking through the subreddit I’m realizing a lot of people seem to have a hard time quitting because it’s a coping mechanism for them. I used to have this problem when I was depressed but since then I’ve been working on myself I’ve started to find happiness and no longer even want to smoke weed. The problem I now have is physical, from nausea to headaches to insomnia I have it all as well as a complete lack of appetite. I cannot eat enough solid food to fill me up without it coming back up. Is there an underlying cause to this or am I just weak.