Had a normal menstruation last month. But now have had light bleeding for almost 3 weeks on and off?

Irregular bleeding. from hormonal imbalance is probably what you have. At the age of 22 a hormone imbalance may cause your body not to know when to shed the lining. This can cause irregular bleeding (“spotting”) between your periods. , if a hormone imbalance is causing your abnormal bleeding, you and your doctor may decide to wait and see if the bleeding improves on its own. If not then bcp prescribed to regulate.