Duphaston - will it lead to blood trails? Like menses flow after 3 intakes? 2 tablets per day.

Went to the gynae, and was prescribe with Duphaston. Expected baby to be at Week 8, based on my calculations of last menses date. Did the scan, and gynae says it’s only at Week 5 Day 6. Started taking Duphaston, and this morning was brown stains. And night time it was like normal menses flow. Please advise if I Shld visit another gynae or go back to the one I visited or to continue on the medicine