Is it obligatory to perform prayer and permissible to engage in sexual intercourse if a few drops of blood appear before menstruation, then these drops cease, and are these drops considered menstruation?

So long as your custom has been to see blood, then for it to cease, then to see blood again two days later, then this initial blood and what follows it is considered a single, continuous menstrual period (haydah mulaffaqah). You are considered menstruating upon seeing it, and you should refrain from prayer and whatever else a menstruating woman abstains from. When the blood ceases, perform ghusl (ritual bath), and you will become pure. However, if it ceases and yellowish or brownish discharge (sufrah or kudrah) appears immediately after it, then its ruling is the same as that of menstruation. Do not perform ghusl until you see complete dryness, indicating the cessation of blood, yellowish, and brownish discharge. It is not permissible for your husband to have intercourse with you while you are seeing blood, yellowish, or brownish discharge. Upon their cessation and your performance of ghusl, he is permitted to have intercourse with you until the blood returns. This intervening period of purity is a valid period of purity, and all rulings applicable to pure women apply to it.