Is it because your period came earlier or some other reason?

Patient's question:

Patient: Female, 22 years old, previously in good health
Current condition: 2 days after her period, had one sexual encounter. Took birth control pills (had never taken them before). Had another sexual encounter 1 week later. 2 days later, experienced spotting. Unsure if it's an early period. Also experiencing dizziness.

Doctor's answer:

Women with infrequent menstruation or frequent amenorrhea should not use birth control pills to induce amenorrhea, as this may lead to long-term amenorrhea. An intrauterine device (IUD) can be used instead. For any menstrual irregularity, condoms or vaginal diaphragms can be employed. Irregular menstrual cycles can be regulated using short-term oral contraceptives.
Menstrual oligomenorrhea: Menstruation occurs only once every 40 days or more, and the flow is very light.
Menstrual hypermenorrhea: Menstruation occurs every 21 days or less, and the flow is excessive.