Question Summary:
Mistakenly offers Salaah during haydh days

Question Detail:

 
1. If someone mistakenly offers salah during haydh days not knowing it was their haydh day, would they have to repeat the sunnah and nafl salahs and tilawah done during those days.
2. I observed a small brown discharge yesterday and today because I am not sure if it would occur upto three days. Should I keep praying fardh and sunnah salahs. 

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykumwa-rahmatullāhiwa-barakātuh.
1) The sunnah and the nafl salats will not have to be repeated. It is advisable to repeat the tilawat of the Quran especially if one intends to complete the Quran. 
Your question is not clear, however, the general ruling is.
2) You should go by your previous habit. If previously, you experienced haydh in three days and you are certain it will be haydh, then do not perform Salah.
And Allah Ta’āla Knows Best
Zakir Husain
Student DarulIftaa
Michigan, U.S.A
Checked and Approved by,
Mufti Ebrahim Desai.