Hi Colleen and @eden I have a diagnosis of SIBO and have done a lot of research (have a health care further nerdy science background 🙂 ) . I've never experienced light headedness after meals, nor have I heard others report that, or seen it listed as a symptom specific to SIBO. We do know of course that everyone is different, and if you experience light headedness 2 hours after meals, you obviously do, I think you might have to be cautious about immediately attributing that to the SIBO. Obviously, if your SIBO is treated and you have some kind of testing to document it is better, and the light headedness also goes away, then you could link the two.
"This is almost certainly the food being fermented by the mass of bacteria in the small intestine and the resulting d-lactic acid, and other products of fermentation including alcohol, circulating in the bloodstream and affecting the brain". There is absolutely no scientific evidence that any of this is happening, particularly any of these substances getting into your blood and your brain. Research into SIBO is still young, and I lot isn't known. While there is speculation that bloating and gassiness could be caused by action of the bacteria on food, this doesn't necessarily mean they are fermented, and nothing has ever shown this, nor that such substances are being produced. Even if they were, and diffusing into the bloodstream, all blood from the GI organs goes to the liver first, via the hepatic portal vein, and those things would detoxified. Our body also is very adept at keeping a tight pH in the blood, and excess lactic acid would be converted into a closely related substance to keep the pH constant. Anyway, none of these substances would get anywhere near your brain. Nor to your muscles to cause any soreness (and would not be present in any amount great enough to do so).
"There are many pages online that purport to describe the symptoms of SIBO."
Yes there are, and this is one syndrome that people really need to be careful with; because sadly there seems to be more BAD info compared to good info with this problem. I suspect b/c the medical community has been so slow to get on board with taking SIBO seriously, it's gotten 'hijacked' by naturopaths, chiropractors, self-appointed experts and all kinds of quacks. Promoting things like you described above. People really need to read carefully, and critically think. There are some patients who are good sources of information. When someone calls themselves "Dr." , check into what kind of Dr. they are. Chiropractors have absolutely no education and training in GI issues. Unfortunately, I think it becomes a vicious circle. In my experience, the medical community, even my Mayo Dr., do not take SIBO seriously, I think partially b/c they see it as something that is associated with quackery.
SIBO and "leaky gut" are two separate issues, and "leaky gut" is another highly controversial issue, and hasn't even been determined whether or not this is a 'real' thing – there is evidence that the permeability of the small intestine likely can be affected by various disease processes. However, many claims made by some sources are just not valid. I won't go into great detail now as this is already getting long. Both of these problems are not 'diseases' in themselves, but things that develop secondary to another problem (and then become a problem). Hence, SIBO will re-occur if the underlying cause cannot be remedied, which is why it is so hard to treat. Often that cause is not known, or can't be 'fixed'.
There is no evidence that SIBO or leaky-gut can cause muscle soreness. However, many people who have SIBO have other medical problems, sometimes many. I'd explore other causes of your muscle soreness and light headedness because it seems a possibility there could be some other cause.
Colleen, I'm not sure if this is where I should be writing this .. or in that other place, but maybe you can move it?