What all can trigger a flareup of lupus arthritis ?

Many things; viruses: So it's unclear exactly what triggers a lupus flare. What we do know it that lupus activates that same immune pathway as viruses (called the type one interferon pathway). So any virus infection (i.e. A cold) can trigger a lupus flare. This is likely only one of many pathways that could induce lupus symptoms. Fyi: there are clinical trials targeting this interferon pathway for lupus pts ongoing.