Sadly elimination is the only way. I started having bowel issues and my kidney health started plummeting (I have kidney problems due to autoimmune condition but that is another story.) so I eliminated everything but the basic stuff from my diet till my bowel movements are normal. Next I added things one by one and waited a few days to see if any change. It is tricky because sometimes there is a lag from when you take something to when the effects are felt. The funny thing is an year ago I didn't have sensitivity to any of these items. I've also paid hundreds of dollars for various tests to see if I can identify these intolerances but none are any good.