Must I pray during the first five days of my menstrual period when the blood comes in intermittent drops?

It seems that the total number of days of your regular period is twelve days. You must observe the menstrual period from the first day you see blood and continue to do so, unless there is an intervening period of purity. If you see purity from blood, brownish discharge, and yellowish discharge, and one of the two signs of purity appears (dryness or white discharge), then consider yourself pure. If blood returns after purity and before the end of the twelve days, observe the menstrual period again, and perform ghusl (ritual bath) upon seeing one of the signs of purity. If blood appears a third time, observe the menstrual period, and so on. If the bleeding exceeds the twelfth day, it is considered istihadah (irregular bleeding) and not menstruation.