Hello,
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Irregular periods along with various symptoms as dizziness,fatigue,heat flashes can be indicative of underlying uterine or ovarian issues as PCOD, endometritis, fibroids, hormonal imbalance, thyroid hormone disorder, eating disorder,stress etc.
It requires a physical examination and a series of investigations as USG scan,hormonal analysis to rule out the exact cause.
Kindly visit a Gynaecologist for detailed evaluation.If hormonal imbalance is detected then usually oral hormonal pills are prescribed. In yoing woman hormonal imbalance/thyroid disorder can be suspected for irregular periods.
Take care!