It could most probably be tonsillitis and a throat infection
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. Consult your primary care physician who will do blood tests and take a throat swab to determine the cause and prescribe appropriate medications.