The next most common trigger is stress. This is a major suspect in lupus, colitis, thyroid disease, and many more. This is a whole subject in itself! We have a self test on the IHC site - DASS - it helps to sort out stress and depression and anxiety. We do training with the Heartmath monitor in the office, sometimes teach mindfulness or use Alpha-Stim. Spiritual support can be vital. Dr. Price is very successful treating stress and autoimmunity also with his Acu-Hyp therapy combining Acupuncuture and Hypnosis.
Other triggers are also important. Adjusting the diet not only to avoid allergens but also inflammatory foods. Yes, these are saturated fats, commercial meats (because of the grain diet the animals are fed) too much starch and sugar. Exposure to pesticides and other toxins (eat organic as much as possible). Many people have chronic infections such as the yeast that was mentioned or another bad bacteria in the gut, or Lyme disease, etc and need to treat this. Lower hormones with aging encourage more inflammation. Adding bioidentical hormones and helping some natural restoration with stress and adrenal treatment will often reduce some of the pain, stiffness, and flair ups. Lastly lack of some nutrients can increase inflammation. If the diet is pretty good, there may still be malabsorption. We often use the FIA test from Spectracell to look for this, or the Metabolic Analysis or Nutra-Eval from Genova. Other strategies include various means for detoxification (a subject for another day) use of supplements for immune balance and support and we at IHC often use the Pleo Sanum isopathic remedies for balance of the body's bacteria and yeast.
It is worth some work to reduce or stop autoimmune disease! These conditions not only cause a wide range of damage, pain, and disability but also tend to cause increased risk of heart disease and cancer!