I have brown discharge then fresh blood for four weeks after 3 months of no menstruation. what could it be?

Periods: AnneT81~ this is heavy bleeding after a very long anovulatory cycle, ie, the endometrium is VERY thick/lush and sheds with heavy blood loss. You should see a Gyn. This occurs after prolonged DEPO use, PCO disease, endometriosis, fibroids etc. TREAT: condisder cyklokapron if bleeding does not stop. thanks

Irregular periods: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections ; hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.