I'm confused over late period pos/neg result, subsequent lengthy duration of bleeding-help?

period usually first wk of month, seemed regular. last period 6th oct. had apparent symptoms of pregnancy, late period. also had andominal cramps and fatigue. took home urine test, fint positive 9th nov. thought pregnant. however, on 1st nov was woke with sever abdominal pain for 20/30 mins. on 16th nov saw slight brownish spotting, only on toilet paper. wen to dr the next day, sent to gynae to investigate bleeding (umed pregnant) however had intenal ultra sound, showed empty womb the dr said 'i'm sorry you're not pregnant' the had blood test to confirm hormone levels - result very low. onthe 19th i bled red blood, i started to get cramps, in quite a bit of discomfort, there was what looked like pieces of pink tissue in the blood and clots, the bleeding was heavy and longer than usual 3-5 day period. the apparance of the blood has varied sometmes red, sometimes brown, and vrying flow. i've bled for weeks now though no more pain for the last 2or so wks. enerally brown lood since then, a times looks like it will gobt reappears, not enough for a pad. still happening now 19/12/08? jst n toilet paper mostl or afer but sometimes a little more or less. what's happening?