The deep dental caries
spread into periapical area can cause sinus infection
which spreads into tonsils too .
A biopsy of the lesion is mandatory to produce a final diagnosis.
Meanwhile,take complete course of antibiotics-analgesics.
INfected pulp within the canals has to be removed completely.
Swish with warm saline and betadine
Take plenty of fluids and nutritious diet.
Please do visit a dentist
for further concern.
Hope this helps.