Welcome to healthcare Magic!
A recent history of flu
and pain in left side of chest along with fever
indicates that you are having a problem with your respiratory system.
It is most likely due to inflammation of the lung covering called pleurisy
or it may be due to a lung infection
which is so common after viral infections.
You should undergo an X Ray
chest and do a complete blood counts.
You should review to a local physician who will know the antibiotics course for you if needed after the clinical examination and report of above mentioned tests.
I hope the advise would be informative and useful for you.