Diseases of thyroid can make your periods irregular which can be improved by treatment. If your thyroid functions are normal you should consult an Endocrinologist
or Gynaecologist and do an evaluation for irregular cycles.
Some females can have inter menstrual bleeding
or spotting 2 weeks after a cycle.
The usual investigations i do for such a patient are Thyroid function tests
, serum prolactin, testosterone
, LH, FSH and an ultrasound scanning of pelvis.
Hope I have answered your querry
Dr Ajish TP