It is great that you are endeavoring to determine triggers for lupus. There are many known triggers but in any individual case the trigger is not known. I suggest that you read a book called " The Autoimmune Epidemic" and you will get a good idea on how AI diseases work...what is the underlying cause and what triggers the autoimmune response.
Most researchers feel that those of us with an AI disease have a set of genes that predisposes our immune system to a disruption and that something triggers a misdirected response on our body. The problem is that there can be many triggers over a long period of time (in some cases) and then a final trigger causes you to become symptomatic. In my case, I think the disease was lurking for at least 15 years before I became symptomatic. At the time I became symptomatic there was nothing that seemed to be a trigger. Remember that a trigger is different from a cause when talking about an AI disease.
When I flash back to that period of my life I was under a lot of stress over a period of years with no other health problems, illnesses, or anything else.
Here is what the Lupus Foundation has to say about causes of lupus:
MCTD (lupus, scleroderma, polymyositis). Diagnosed 2005. Kidney, liver, GI tract, dysphagia, raynauds, Barretts esophagus, quadriplegic in 2005. Recovered and now active in skiing, tai, chi, hiking, golf. Meds: prednisone 2.5mg, imuran 25mg, amlodipine, benazapril, omeprazole, potassium, folic acid, vitamins, maxide and various supplements and vitamins.
Remain optimistic and you can overcome the odds.