thanks for your query.
After a delivery ( normal or cesarean ), it is common to have menstrual irregularities for some months, but 14 months is too long for them to persist.
You could be having menstrual migraine
- commonly associated with headaches
Other causes of menstrual irregularity could be stress, anxiety, ongoing lactation
, surgery, thyroid disorders, polycystic ovaries
, damage to the endometrium or some other concurrent medications.
Also, a variation of 4 days is within the normal range.
Please consult your gynecologist for detailed evaluation.