How Long Will It Take To Get A Period After Taking Duphaston?

Hi, I am married since 5 years and try to conceive but yet no positive result. I have very irregular cycle, my last period was on June 23, few days ago I visited my doctor and she did pregnancy test but it was negative, so she suggest me to take Duphaston 10 mg . I was started Duphaston on 12 of August for 10 days. After 3 days of completed medicine on 24th of August I have sharp pain on my stomach whole night and day with little pink discharge. Is this my period? If not then how long it will take to get period after taking Duphaston? What about this continuous sharp pain, which I was not face before I am really worried.