Stopping Duphaston mid-cycle commonly triggers a heavier-than-usual withdrawal bleed with clots, which fits your timeline. Your last scan also showed a cyst on your left ovary being watched, so the bleeding and pain could be linked to that rather than the medication alone.
Next Steps
Track how many pads you're soaking (more than one every 1-2 hours is heavy), and see a gynaecologist or visit a local hospital where you're travelling, so the pain and cyst can be checked together, ideally with a repeat ultrasound.
Health Tips
Go in urgently if you feel faint, the pain suddenly worsens or shifts to one side, you develop fever, or bleeding doesn't ease over the next day or two.