Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
Yes, intake of an emergency birth control pill like
postinor 2 can cause early & light bleeding before your next expected period. The bleeding you had must be
breakthrough bleeding which normally occurs within 3 weeks of intake of Unwanted 72 pill. This is normal feature of intake of an emergency birth conrol pill & you should not be much concerned about it.
This type is bleeding is different from a period is lighter in quantity & occurs for shorter duration of time. Breakthrough bleeding most probably means that intake of postinor 2 was succesful in preventing
pregnancy.
Don't take postinor 2 or an
emergency contraceptive pill too frequently. Use condom or regular contraceptive pill regularly as method of
contraception in future. Emergency birth control pill can cause irregular bleeding & other serious side effects.
Refer to a gynaecologist for more queries
Don't worry you would be fine
Hope this information helps