Is it obligatory to stop praying and perform ghusl upon seeing light, scant, and intermittent blood after the the usual cessation of menstrual bleeding?

Every blood a woman sees during the time she is able to menstruate is considered menses. The recurring blood you saw is considered menses. The intervening period of purity is considered a valid period of purity, so a woman must perform ghusl if she sees purity by one of its two signs (dryness or white discharge). Then, if blood returns, she becomes a menstruating woman again and performs ghusl after it stops. Therefore, it was obligatory for you to perform ghusl and pray when the blood stopped. Then, if it returned to you, you would become a menstruating woman again and perform ghusl after it stopped again, and so on. If you missed prayers during the intervening period of purity, you must make them up.