Hello - I heard that many people carry many diseases or cancers in their bodies and it just takes a "trigger" to make them active - because everyone is different it's hard to pinpoint what triggers each person. For our daughter I think it was stress & anxiety that triggered crohn's. She still hasn't found the drug that works - a year later.....we're still trying and hoping but she's at the point of feeling disillusioned with doctors and the overall medical community....
Stress and trauma do not cause any auto-immune diseases but can definitely trigger them if you have a pre-disposition to it. The initial trauma was nasty enough. I feel for her and hope she can get things under control.
Just like the others have said stress and trauma cannot cause you to have an auto immune disease but a certain event in your life can trigger it if you have the gene for it or a predisposition for it.