I have a cycle of 21 days(excluding the five day cycle). I always get down on time and have a prefect flow. But this the flow is very less and I have severe pain in lower back and cramps in stomach. Also week before I got my periods I had yeast infection which was almost fine the night before I got down. I have had 2 meftal spas also one yesterday morning and another ar night but there isn't any improvement in flow. Only when I go to the loo the blood clot flows out otherwise the flow isn't there much. What could be the reason and what medicine should I take?