I start bleeding again days after my period. why?

Bleeding/period: In mid-30's, estrogen levels are much higher than in one's 20's. This makes the lining of the uterus much thicker, and degeneration of the lining can cause heavier bleeding, which can cause some clotting. The clots block the cervical canal, and before they dissolve, will stop the bleeding, only to resume after the clot is expelled. If you suspect pregnancy, get a serum HCG test for certainty.