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If you had been sexually active after having the withdrawal bleeding (after stopping with birth control use), then the lighter spotting could indicate probable implantation bleed. If the symptoms suggestive of early pregnancy (spotting, brown discharge, nausea, sore & bigger feeling breasts, areolas getting bigger, absence of usual pre-menstrual symptoms) remain persistent, or if periods do not start within 10 days of expected period dates, or if you get abnormal periods, or if you suspect chances of pregnancy, consider visiting your doctor/gynecologist at the earliest for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately). Be in regular monitoring and follow-up with your treating doctor/gynecologist and report any new/abnormal symptoms immediately. Take adequate rest. Drink plenty of water. Maintain healthy diet.
Take care.