Hi ! 6 weeks duration of the cervical lymph node enlargement labels it as a chronic lymphadenopathy. I am not aware to which region you belong to. In Asian region, tuberculosis is a common cause of chronic cervical lymphadenopathy, but it may also be associated with fever, loss of appetite and loss of weight. Other causes may be many benign and malignant conditions of the lymph nodes and I do not want to confuse you by naming all these. However, I would definitely suggest you to visit your family physician/medical specialist at the earliest, and get yourself clinically examined, who may advise you for some routine investigations, and also a FNAC(Fine needle aspiration cytology) which is a must to diagnose with certainty about your condition. The management will depend on the reports. Wishing you an early recovery.