Is the condition mentioned in the specified dates considered menstruation or istihada (non-menstrual bleeding), and what is the ruling on fasting and prayer in this situation, especially during Ramadan?

First, one must understand the general rule for distinguishing between menstrual blood (hayd) and irregular vaginal bleeding (istihada). The maximum duration of menstruation is fifteen days, and the minimum period of purity (tuhr) between two menstrual cycles is fifteen days.

Therefore, if the interval between the two ends of the bleeding is less than fifteen days, or if the interval between the two bleeding periods is fifteen days or more, then the returning blood is considered menstruation.

However, if the interval between the two ends of the bleeding is more than fifteen days, and the returning blood lasts for less than fifteen days, then the woman is considered to be experiencing istihada.

In this specific case, the second bleeding is istihada, the third bleeding is menstruation, and the fourth bleeding is istihada. A woman experiencing istihada must take precautions (e.g., use a pad) and perform ablution (wudu') for every prayer after its time has begun.