You must take antibiotics for the infection and see an ENT specialist
You need to get done a tissue diagnosis of the enlarged lymph
Fine needle aspiration cytology- in this the tissue of the lymph node is aspirated by a needle and then checked under the microscope.
You can also get done - if your doctor advise you an excision biopsy
of the lymph nodes and then the tissue diagnosis can be done .
You must get these tests done as you are getting loss of appetite etc.
There are few blood tests also like CBC,ESR
and even Chest Xray is needed to be done.
If in doubt do reply