Considering SSRIs are prescribed for IBS (the gut has a lot of serotonin in it) and anxiety disorders (the brain also uses serotonin), I could see this being related.
For me personally, anxiety would cause me to have gut issues (i.e. bloating, feeling sick, diarrhea, etc). After a while, the reverse started happening too, things like feeling bloated triggered my anxiety.
Just changing me diet to include a lot more fibre and cutting back a lot of processed carbs helped reduce the stomach problems which resulted in less anxiety.
This! I had the same issues during high school. First it started with unnerving belly issues, bloating and so on. It turned out to be some virus, what the doctor concluded. It just took me to recover a bit, it stopped gradually. But that really impacted my self-esteem, all the noises my stomach made and the constant thinking how will it be today, and a few episodes of severe lightheadedness. I started getting psychosomatic symptoms after everything cleared, when I would start thinking of it, basically the reverse.
Today I have some residues, I think. Bursts of hypochondria here and there, psychotherapy helps me keep it under control. Although a lot more things went into developing that one :-)
There was a recent small scale study[1] that suggested taking probiotics could increase the time for the gut microbiota to return to normal. The biggest bang might have been a fecal transplant of cultures taken from your own gut before you started on antibiotics. The study is more suggestive than conclusive because of limited sample size.
