Re: ayyam ul baiz!!
In some hadiths, it is narrated to fast on Monday, Thursday and Monday of each month of lunar calendar i.e., starting from either Monday or Thursday. The hadith in support of fasting three days is quoted below:
Book ‘Fasting’ of Sahih Bukhari, Hadith No. 202.
Narrated Abu Huraira: My friend (the Prophet ) advised me to observe three things:
(1) to fast three days a month;
(2) to pray two Rakat of Duha prayer (fore-noon prayer); and
(3) to pray Witr before sleeping.
Book ‘Fasting (Kitab Al-Siyam)’ of Sunan Abu-Dawud, Hadith No. 2446.
Narrated Umm Salamah, Ummul Mu’minin: Hunaydah al-Khuza’i reported on the authority of her mother who said: I entered upon Umm Salamah and asked her about fasting. She said: The Apostle of Allah 
used to command me to fast three days every month beginning with Monday or Thursday.
Almighty Allah knows best.