@lamd I did an autosomal DNA test at ftDNA for $49. Then, I submitted the results to Vitagene. (it was $49 when it opened, then went to $99, don't know what it is now). But there are several companies that compete in the field now. Just search online. There are many: https://www.google.com/search
Go to the Monash University for the best elimination diet! They identified the most common problem food groups. You eliminate them all and then ad each group back in one at a time. It was so easy and it clearly worked and gave me my life back. Most people think they can do it and then quit. You can't you have to stay with it. Most people do it for about a year, the novelty wears off and they give in. It took me 3 years of trying then it stuck. I have a very WIDE diet but it just stays within the confines of what I had to give up in the process. So things came back in a different way. (like "essence" of garlic no garlic itself. Scallion/chive tops no onion.)
I also had to deal with SIBO. Some people don't get tested so they don't know they have SIBO which must be periodically dealt with on top of the IBS!
https://www.monashfodmap.com/