Thanks for the query.
Delay in periods can occur due to many causes.
Recent illness can also affect the menstrual cycle.
Better to go for urine pregnancy
test to come to one conclusion. Tonsillitis
can present with throat pain, difficulty in swallowing etc symptoms.
So, better consult ENT surgeon once and get examined and take treatment.
If he recommends go for throat swab culture and sensitivity.
If pregnancy test comes positive, consult gynecologist once, undergo ultrasound
If you want to continue the pregnancy, take regular antenatal checkups.
Usually mild illness due to infection may not have much effect on the fetus.