So have you seen your OB/Gyn about
any of this? I don't know how CD and vaginal bleeding could be related. On the other hand, lots of women have an increase of abdominal symptoms with their menstrual cycle. Prostaglandins in the pelvis around ovulation or menstruation definitely can give you diarrhea.
Heavy menstrual bleeding can be due to several different things. If you are not menstruating monthly (it's not clear from your post, but did you skip 3 months of cycles?) then you are probably not ovulating. Your CD could interrupt ovulation (I think that CD can be a cause of endocrine dysfunction), or perhaps your ovulatory cycles are awry for other reasons. or you could have fibroids in the uterus, which could definitely lead to heavy bleeding.
Call your OB/Gyn.