Eh, spotting coklat macam tu memang boleh jadi scary sis, lagi-lagi kalau haid kau biasanya punctual je 4 hari. Since urine test dah negative and dah try ubat tapi still berlanjut, I think better you go for that scan sooner rather than later, tak rugi pun, and at least doctor boleh tengok apa yang tengah berlaku kat sana. A few of my mum friends pernah alami coklat spotting yang linger, and when they did the ultrasound it gave them peace of mind, some kena hormonal imbalance, ada yang polyp or cyst je. Don't wait till 15 days kalau still keluar lah, better be safe and get it checked.