Thanks for the query.
pills can cause irregularity in menstruation
Intermenstrual spotting, breakthrough bleeding
etc. are some of these side effects.
As your wife having the bleeding since 15 days, better to consult gynecologist once and get examined to rule out any other possible causes of bleeding.
After that she can take additional dose of hormones to control the bleeding. Possibly she may not have the problem in future.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429