Hello and hope you are doing well.
It could most probably be tonsillitis and a throat infection. Throat pain, difficulty swallowing, fever, scratchiness in the throat, post nasal drip, malaise and loss of appetite are symptoms of tonsillitis. It can be caused by bacteria like streptococcus or it could be a viral infection. Bacterial infections need antibiotics. Infections in the throat cause lymph node enlargement. As, it is subsiding with the infection, it is the most likely cause.
Tonsillectomy is advised if there is recurrent streptococcal tonsillitis, recurrent peritonsillar abscess and chronic tonsillitis.
Hope this helped and do keep us posted.