Duphaston - 1st visit to gynae, calculated week 8, but at visit scan shows week 5 day 6

Gynae informed that the calculations may be wrong/inaccurate. However prescribed Duphaston / 2 tablets a day. I just started taking ytd, and this morning I have brown stains, now at night I’m having blood trail, like normal menses with clogs and etc. Is this normal? Should I visit another gynae to reconfirm? #veryworriedmum #First_Pregnancy