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Variation of 5-10 days in your menstrual cycle length is considered to be normal as long as your periods are regular. Hormonal and period pattern can be affected by changes in lifestyle, changes in diet, exercise level changes, changes in sleep habits, changes in stress levels and environmental changes. Other causes like hormonal imbalances, thyroid hormone abnormalities, endometrial changes PCOD, anemia, etc should also be ruled out. You can consider going ahead with visiting your doctor/gynecologist for thorough evaluation done to look for underlying cause for changed period pattern. Treatment as appropriate would be started to help you get back your period pattern and regulate them (based on examination findings and investigation results). Drink plenty of water. Maintain healthy diet. Be in regular follow-up and monitoring of your treating gynecologist/obstetrician and report any unusual/abnormal/new symptoms immediately.
Take care.