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.