SIBO is similar to leaky gut...leaky gut is also blood borne in case you did not know. How do you think the SIBO gets into the blood system if there was no weakened intestine wall to begin with?
SIBO, leaky gut, IBS, and candida they are all similar and it is really hard to distinguish which came first and which one you really have even with testing. I'm sure it is hard to say that she has "this" just from simple symptoms and conditions that she described.
IMO SIBO is simple Sugar and leaky gut has wilder range of triggers such as gluten, soy, corn etc. and FMO3 is the TMAU which are all similar and only way to distinguish them is through proper testing.
That's why I only mentioned leaky gut since it contains broader range of allergens. BTW if you are going to tested for gluten sensitivity you have to eat food that contains gluten so in your blood stream they will be able to detect the allergen to gluten.