Most
viral sore throats go away after 3-4 days and are accompanied by other
symptoms of muscle aches, low grade fever, and runny nose. If your throat is
beefy red and swollen, or has white patches, or you have high fever, you
should be examined.
Lymph
tissue swelling in the back of the throat, as you are describing, can also
appear in allergies, but is most common in a viral infection.