A single missed dose of the progesterone your doctor started for the heavy bleeding after your i-pill is a common reason for the spotting you're seeing now. It doesn't undo the treatment, but staying consistent with the remaining doses matters for controlling the bleeding properly.
Next Steps
If it's been less than a day, take the missed pill now and continue the rest of the course on schedule. Avoid doubling up to catch up. Let your prescribing doctor know about the missed dose and the spotting so they can confirm the plan is still on track.
Health Tips
Go back to your gynaecologist the same day if the bleeding turns heavier than a normal period, or if you feel dizzy or very weak.