thank you for your query.
As you are 3 days overdue, why dont you take a simple home urine pregnancy
test to know whether you are pregnant or not ?
The altered bleeding could be an early pregnancy, an early miscarriage
or an ectopic pregnancy.
Stress, anxiety, emotional trauma, travelling, weight gain or loss - all can cause such bleeding.
Thyroid disorders, high prolactin
levels and polycystic ovaries
also could be the cause.
If your pregnancy test is negative, visit a gynecologist for a detailed diagnosis.
Please have safe sex in the future.