Hi Thanks for the query. I understand your concern. You have completed your course of Tamiflu. Suffering from extreme weakness, nausea, back ache and cough. * Though your general weakness could be due to an attack of flu. * Backache can be stress of coughing or part of weakness and nausea secondary to the medicine. I would suggest for review by treating doctor for - Prescribing vitamins & other nutrients as per need (after blood counts) - Evaluation of basic infection &need for more flue drug. - Prescription for cough (just a Zyrup if non-infected secondarily by bacteria/addition of antibiotic as per need. * Till then if you don t have any fever you can manage by over the counter drugs like Ranitidine (for nausea), cough syrup ,multi-vitamins & high protein light diet. Take rest Thanks. Dr. Vasudha Jayant Athavale, General & Family Physician