** Thanks for contacting with your health concern 1. The symptoms could possibly indicate infectious arthritis [since risk factor for the same include suppressed immune system [and history of SLE is present] 2. As genital herpes has no symptoms, so one can be infected and contagious without knowing it, so you may ask for: -PCR blood test; which can tell you if you have genital herpes, even if you don t have symptoms. - Cell culture: your health care examiner, will take a sample and look for herpes simplex virus [HSV] under a microscope. PS. another likely cause to be excluded is reactive arthritis induced by bacterial vaginosis which responds well to metronidazole therapy. 3. Your attending Doctor may take x-rays of the affected joint to rule out other conditions, and MRI may be needed if the joint cannot be easily examined or aspirated and treatment started with antibiotics and splinting of the joint, followed by physical therapy.