Hi. Thanks for your query. Noted the history and understood your concerns. 3 weeks of headache, lymph node enlargement, cough, sore throat and pain in abdomen can have a definite cause. You can have anti-inflammatory medication and multivitamins at home. But since you are suffering for the last three weeks it is highly advisable to have the following: Consult your Family Doctor for clinical evaluation, examination and investigations of blood like CBC, culture and sensitivity. Ultrasonography of neck for the lymph nodes and FNAC to know the cause of enlargement. A course of an antibiotic, anti-inflammatory medications should help you get the relief.