hi. noted history of cholecystectomy, recent episodes of nausea, night sweats and fatigue. may i ask what post-operative medications are you currently taking in? some of these can possibly cause the nausea. but your symptoms may also not be related to your surgery. it can be a systemic viral illness which can resolve spontaneously in a few days time. it is best if you do a follow-up consult with your surgeon, for physical examination and clinical evaluation. diagnostics (such as complete blood count, chest xray, etc.) and management will be directed accordingly. low fat diet is also advised. hope this helps. good day!! ~dr.kaye