Causes of abnormal uterine bleeding are many - ( but the first things to be ruled out include uterine, endocrine -Hormone related) If blood loss is for longer durations such as 22days, I would advise an ultrasound scan to assess the uterus / cavity, Blood tests to check your reproductive hormones including thyroid function and prolactin levels. If all os the above are normal then check clotting. If no organic cause found then it would be prudent to consider a contraceptive pill with a view to regulate your periods as they are used not just as a contraceptive. hope this helps, regards.