What Causes Vaginal Spotting Post Menstruation?

I am under contraceptive pills (yasmin) for the last 6 months in USA. I was suffering from spotting even after the menstruation cycle was over for the last 3 months. Since I am without a health insurance I asked my doctor back in India about the issue and she suggested me to have double dose of the medicine i.e. 42 tablets in 21 days cycle ( 2 * 21=42 tablets ).Now that I have run out of medication I am still having the same problem (spotting) like before.What should I do taking into consideration that I am leaving for India in February beginning?