Thanks for the query.
Stress and strain due to fever can lead to fluctuation in the hormonal
levels, which can alter the menstrual cycle.
As you had protected intercourse
and that too at the last days of your cycle the chance of pregnancy
is very less.
So you better wait for one more week by that time possibly you will get periods. If not consult gynecologist once and undergo physical examination and ultrasound
to find out the cause for your delayed periods.