There is nothing to be scared of, relax. It could a simple lymph
node enlargement due to common viral infections of the throat.
You could do salt water gargling with lukewarm water thrice daily for next few days. The maximum benefit will be from taking a course of oral antibiotics
. Whether it is required in you, can be judged by a Physician after your general physical examination.
There is nothing really serious here for you to worry.
I wish you quick recovery.