What should I do in Ramadan if menstruation stops for a few hours and then resumes, and I haven't performed ghusl because I'm not certain of purity? Is fasting permissible without ghusl and prayer in this situation?

If a woman sees the sign of purity (either dryness or white discharge), she must hasten to perform ghusl immediately and should not delay it if the delay would cause her to miss a prayer. After ghusl, she is ritually pure and has all the rulings of pure women. If blood returns after that, she reverts to being in a state of menstruation. The preponderant opinion is that purity is valid even if it occurs intermittently during the menstrual period. So, if a woman fasts a full day in Ramadan after seeing the sign of purity and performing ghusl, her fast is valid, and she is not required to make up that day. If she becomes pure before Fajr and intends to fast but delays ghusl, her fast is valid, but delaying ghusl beyond the prayer time is a sin.