Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
Yes, Intake of a plan B pill can cause vaginal spotting. Vaginal spotting or bleeding you had must be
breakthrough bleeding which normally occurs within 3 weeks of intake of a plan B pill. This is normal feature of intake of Plan B pill & you should not be much concerned about it. This bleeding is due to high dose of
levonorgestrel in a plan B pill, which disrupts your normal menstrual cycle & cause this type of bleeding.
Breakthrough bleeding most probably means that intake of plan B pill was successful in preventing pregnancy. Now your next period may also be delayed.
Don't take a plan B pill too frequently. These pill can cause
irregular periods & other serious side effects. Use condom or regular
contraceptive pill regularly as method of contraception in future. Therefore you should avoid these in future.
However blood during urination in absence of vaginal spotting could be a symptom of some
urinary tract problem such as UTI.
Refer to a gynaecologist if problem persist
Don't worry you would be fine
Hope this information helps