Birth Control and Bleeding

Are you still bleeding or experiencing spotting while on the pill? If this is the first time you started using birth control pills, it is normal for new users to bleed during the first three months while on the pill. If you continue to bleed while on the pill, speak with your doctor to see if you should come off the pill for a little while. Once you get back on the pill, there should not be anymore bleeding or spotting.
Bleeding or spotting while you are currently using birth control pills is known is breakthrough bleeding. If you are still bleeding or spotting, you should try switching to a different pill. Bleeding or spotting usually indicates that your pills are not as effective as they should be (additional methods of birth control when you are bleeding or spotting are recommended). Spotting is also a symptom of a sexually transmitted disease known as Chlamydia.
This is something I am very familiar with. I used to be on the pill and experienced abnormal breakthrough bleeding, once for three months. At first I thought I was menstruating, but when it wouldn't go away, I knew something else was up.
However, if you are bleeding after intercourse with your partner, that could be a whole other problem. "f you are bleeding after sex, check with your doctor immediately. Vaginal bleeding after sex can indicate the following:
Cervical Dysplasia (precancerous changes of the epithelial cells that line the cervix)
Chlamydia (bacterial infection transmitted through sexual activity or contact with semen, vaginal fluid, or blood)
Gonorrhea (an STD caused by bacteria. Pharmaceutical treatments available)
Vaginitis/Cervicitis (inflammation, swelling, and/or infection of the vagina or cervix)
Cervical Polyps (smooth, red or purple, finger-like growths grown from mucus layer of the cervix or the cervical canal)
Trichomoniasis (STD caused by protozoan)
Vaginal Yeast Infection (overgrowth of the normal fungi in the vaginal area)
Endometritis (inflammation of the endometrium)
Adenomyosis (when an endometrial tissue attaches itself to the uterus, or another organ, and grows outside of the uterus)
Uterine Polyps (overgrowth of the endometrium causing protrusions into the uterus)
Fibroid Tumors (a benign tumor)"
(http://www.birthcontrolbuzz.com/blog/2008/12/birth-control-and-bleeding.html)