Welcome to HCM,
A simple sore throat
should resolve by this time because now a days medicines are very effective, I do not know if you have taken any medicine or not but if it gets complicated or secondary infection.
Proper ENT check up with if any thing is suspected a X ray PNS and blood work up may be required.
A sinus infection
may be there along with tonsillitis and pharyngitis
,if any abscess forms then it is serious condition some time a simple streptococcal infection
damages kidneys or heart?
Please do not worry about cancer but proper check up is must,if ant thing is suspected a proper biopsy may be done.
There is also a possibility of allergic problem so please consult a ENT Surgeon and hopefully with prescription treatment you should improve in few days time.
In the mean time hot saline gargles and simple analgesic like paracetamol
will help to give some relief.