Brief Pain Exposure Therapy (BPET) For Nociplastic Pain

Inclusion Criteria: * Able to read, write and speak English * Internet access and audio-visual conferencing capability (e.g., Zoom meetings by phone or computer) in the home Fibromyalgia participants must have: * Physician diagnosis of fibromyalgia * OR: meet 2016 American College of Rheumatology (ACR) Criteria for FM: Widespread pain index score is ≥ 7 and symptom severity scale score is ≥ 5, or widespread pain index score is 4 to 6 and symptom severity score is ≥ 9 * OR: have pain self-reported in 4 out of 7 body regions in the General Sensory Sensitivity (GSS)-brief body map AND Opioid Use Disorder diagnosis by a physician. Lupus participants must have: * Physician diagnosis of systemic lupus erythematosus * AND: Have pain self-reported in 4 out of 7 body regions in the GSS-brief body map * AND: No change in medications or steroid dose for one month prior to entry (to avoid oscillation of steroid dosing during the study due to active disease). Chronic Low Back Pain participants must have: * Low Back Pain for at least half the days over the past 6 months * Over the past 7 days, an average pain intensity of at least 4 out of 10 Exclusion Criteria: * Indication of a co-occurring (non-fibromyalgia OR non-lupus) cause of chronic pain (e.g., inflammatory arthritis, other autoimmune disorders, spinal cord injury, cancer) * Currently receiving cognitive-behavioral therapy or other psychological therapies for pain * Open litigation regarding chronic pain in the past 1 year, as assessed in preliminary study screening. * Inability to provide informed consent and complete study procedures (e.g., indications of suspected major cognitive impairment via observations of study staff during consenting) that would preclude comprehension or participation in study protocols. * Pregnant or breastfeeding * Any other diseases or conditions that would make a patient unsuitable for study participation as determined by the site principal investigators. * Lupus group only: taking \>10 mg prednisone (or equivalent steroid) dose per day as an indicator of ongoing disease activity (with no other strict exclusions based on medications) * Chronic Pelvic Pain group only: surgery for any chronic pelvic pain related condition in the past 6 months * Chronic low back pain only: scheduled back surgery; leg pain that is greater than your back pain