Hi Lupus is a chronic inflammatory disease that occurs when your body s immune system attacks your own tissues and organs.No two cases of lupus are alike symptoms wise as manifestation largely depends on the system or organs touched.Lupus can cause all the symptoms you describe including migraine-like headaches, fatigue and joint pains.Its true other medical conditions like sepsis can give you that presentation but positive lupus test more likely points to it.I will suggest you run the test again in a different laboratory. Lupus might not have any treatment but symptomatic management can give you a normal life.So, do not wear yourself down in thoughts. I will advise you go back to the Doctor or see a Rheumatologist for investigation and early management. Hope my answer will help you Best regards