Good morning @annedodrill44- Hello. Everything works in conjunction with the brain, even the gut. What is the name of of this doctor that you mentioned? I am very glad that you feel much better. This could also be the result of a healthier diet that you have started. When you start a new diet and then a medication that you have never taken before neither change can be credited with success. You need to be very careful what you read on-line. One research by a doctor has to be peer tested over and over again.
The gut-brain Connection axis has just really started to take off in research. However the research has not indicated that probiotics alone work.
https://en.wikipedia.org/wiki/Gut%E2%80%93brain_axis
https://psychscenehub.com/psychinsights/the-simplified-guide-to-the-gut-brain-axis/
https://www.bbc.com/news/health-43815370https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4662178/
https://www.bbc.com/news/health-43815370
And there are a lot of claims that probiotics don't work at all. You can google lots of these claims. Plus they are not regulated. I argue that anyone should just go out and buy "the highest number of Lactobacillis you can find". No one should do this on their own, without guidance from their own doctor.