Hi Em,
Welcome. I'm a 51-year-old guy, with a long-term flare lasting about a year. That may have been the onset of Crohn's or it may have onset 7 years ago with a partial obstruction.
Crohn's disease is an autoimmune disorder, which means it involves multiple organs and body systems, and effects different regions and areas of the body. My ortho surgeon calls it a "systemic" problem which is very accurate. The two most obvious being the immune system and digestive system. Also depending on it's preference, Crohn's can manifest in one of 5 digestive areas: Gastroduadenal CD (upper GI), Jejunoitis (between duodenum and ilium), Ileitis (iliem - more common), Ileocolitis (ileum & lower bowel - also more common), and Crohn's Colitis (or "Granulatomous Colitis" involving lower bowel). Just because Crohn's disease manifests in one area doesn't mean it won't progress to another area.
Crohn's disease causes one (or more) of three major problems to our gut. 1. Fibrostenotic which means it causes "strictures", narrowing, or obsstruction in the intestinal wall. 2. Perforation which means it causes holes that allow leakage of the bowel that result in absesses, fistulas, or other abnormal connections from the bowel to the bowel or other organs, and 3. Inflammation which means localized swelling, ulceration, lesions, sores, and the like. All nasty stuff.
Because it is an autoimmune disorder, Crohn's disease can and often does have "Extra-intestinal Manifestations (EIM's)" that effect joints, skin, eyes, liver (fatty infusion), kidneys (stones), and "psycho-social" (anxiety and depression)
Fatigue is part of this disease because of the inflammation process which is somehow initiated by the immune system, and the immune response. The immune system is doing double-duty which the body is not designed to do. So it takes more energy to operate the immune system which means the body has to figure where to get the energy from. Obviously it's not there so we get fatigued.
With my case, I get fatigued when I'm having a flare or "active inflammation" going on. I'm being treated with EntocortEC for about 3 weeks now, and I believe it is working. My symptoms have become mild, and the inflammation has gotten less active because I haven't had fatigue a symptom during the past 3 weeks. So if you are feeling fatigued, you are probably having an active inflammation, an absess or fistula, or a blockage or stricture. I'm pretty sure any of those conditions will bring about an autoimmune response and fatigue - PLUS a lot of pain! Usuallly when the Crohn's flares are under control or in remission, the fatigue subsides.
But until any of us gets effective treatment, we all have to live with fatigue as good as we can. For me it was missing days of work without pay, lots of naps and rest, and general "unproductiveness" for the past year. It's not a pleasant disease nor is it easy to get under control.
I'm not an expert, but I read a lot and absorb as much information that I can. My girlfriend has Crohn's Colitis, and I have Crohn's Ileitis. The more we know and understand about this disease, it becomes easier to manage and live with the symptoms. Glad you could join, and hang in!
Joseph