Hi Span, I have some experience with this. Well actually my overall experience is that of switching between substances and behaviors when I stop using one I'd start using another. For example I have a long history with alcohol and marijuana. Awhile back, when I moved to a new place where I no longer knew where to get marijuana I also started taking antabuse to chemically stop myself from using alcohol, but was not active in a recovery program at that point. No surprise I started drinking cough syrup with DXM as just another way to get high to numb myself out from reality. Then I stopped taking cough syrup once I figured out where to get marijuana again. Awhile later I got sober from substances in AA but found myself binging and purging on junk food once or twice/week my first few couple of months sober in AA too, though I stopped that after a few months as AA started to provide some relief, that was not the end of my problems.
Overall when I was using it just came down to wanting to escape from and numb myself from reality. For me I never really understood what was causing this, and while AA was helpful it wasn't fully what I needed for where I was at to get to the root of the issue. It finally has taken therapy to resolve stuff that happened to me a long time ago which was affecting my present in an ongoing way without me even realizing it because it had just become the background noise/pain of my reality. For many/most people though joining a group like AA or another recovery program with group support is all the support they need to get and stay sober.
I can't say how much of this might apply to you, but it is what happened with me. One thing I can say is that I do think if someone is sober and not working a recovery program, they should consider becoming more active in their recovery to see if it helps (group support of any sort is really key in my opinion), and if they are in recovery but not feeling relief from underlying discomfort for whatever reason it might be helpful to see a specialist/therapist if they suspect there are things going on under the surface which are causing them ongoing pain/anxiety/discomfort which their recovery program by itself doesn't seem to be addressing.
I hope that helps.
ps if you're new to recovery programs/group support, one safe and fairly non-intrusive way to start might be to check out the Class of December Support thread on this forum, and maybe read through it and see if its something you might be interested in joining.