I too have IBS and after reading many posts feel kind of lucky to only have a bout once a week. It doesn't last long but I am tired all the time and as a competitive athlete that's not fun. After 15 years of this it now really wears on me especially not knowing when it might flair. In my research to learn more I happened upon Celiac Sprue AKA gluten intolerance. Like many of you I am lactose intolerant which goes hand in hand with IBS. I went to my GP the the day to ask for a Gluten or Celiac blood panel and she dismissed me faster than the last class on the last day of school. I was floored. She wants me to go to a gastro specialist-no way! Not doing a barage of tests and running up a huge medical bill so they can tell me I have IBS!! Any of you been tested?? If not see if you can be the symptoms mirror IBS. I am persuing alternative health practitioners to just get the darn blood test. What a huge relief if just cutting wheat out of my diet could put an end to this!!
The best way to determine if you have celiac is to go gluten free, if you're not going to have the testing done by a GI doc. Contrary to what others may believe it's not that hard of a diet, there are alot of gluten free products on the market, I tried a GF diet once in my quest to determine my problems and found some delicious products, my favorite was the gluten free pretzels..lol! Lactose intolerance also goes hand in hand with gluten intolerance.
Celiac is when the villi of the intestines have been damaged and often the GI doc doesn't take enough samples to biopsy to even determine if that's the case.
The best bet would to do at least a couple of months of going gluten free, if you feel better you're probably on the right track, though it can take longer to heal the damage to the villi if you do have celiac.
But, a caution...if you do decide to see a GI doc and get tested for celiac, DON"T go gluten free until after the testing as the villi can begin healing and the doc would all the more likely to miss it.
Having celiac can lead to other health problems, such as malabsorbtion, which could explain your fatigue. Would your primary doc be willing to test for your ferritin, B-12 and iron levels? That could give you a clue too.
Good luck in whatever you decide.