I've had the same thing with several anti-depressants. It is due to the drug interfering with prolactin which is a hormone that affects milk production but also messes with your periods. In some people they start producing breast milk but in others it messes with their periods. I got to the stage where I was bleeding every day. Some meds are worse than others and Abilify is definitely one that can cause this problem, I found Cymbalta and Effexor are horrid too. It was my gynaecologist that identified my problem so I'd recommend seeing one just to rule out any other causes.