Irregular periods don’t only mean late or missed periods, but also periods that are early, that last for longer than usual, or are irregular in any other way.
There is also spotting that may happen mid cycle which may or may not be cause for concern.
When you have a longer than normal period that goes on for much longer than usual, that can be due to uterine tumors. These may be malignant or may not be any cause for concern, but they do require to be investigated.
In between periods you may notice spotting which may be due to a polyp or a cyst in any of a number or places: the uterus, cervix or vagina and may also require investigation. If menstrual bleeding is accompanied by a sharp abdominal pain, a doctor should immediately be consulted since it could be a sign of an ectopic pregnancy.
A thyroid imbalance can cause irregular periods as can problems with the pelvic organs, such as imperforate hymen, polycystic ovary syndrome, or Asherman’s syndrome. Other problems such as irritable bowel syndrome, tuberculosis, liver disease, and diabetes can also cause irregular periods, but this is relatively rare.