Why does my cervix drop lower on my period? By the 2nd or 3rd day, it becomes extremely hard to put a tampin in and its very painful.

Cervix. Hmmm. Have you had vaginal delivery, a recent pap, std evaluation? Careful with tampons, never leave them inside for more than a day. Get examined, you need a pelvic-vaginal exam and testing.
Pelvic Pressure. With menses, the pelvis retains water. The uterus moves . This displacement depends on the ligaments that support the organ. If there is prolapse of the uterus or cervix, it may become prominent during this time of the month. Consult with your gynecologist.
Menstrual Clots. Some clotting with menstrual flow is normal. Size matters ! golf ball size clots , heaviness sensation and cramping should be evaluated. A pelvic examination and ultrasound may help .
Cervical Prolapse. The uterus is a dynamic organ. I moves ! the displacement depends on support by ligaments the can stretch beyond recovery. Menstruation brings swelling and inflammatory changes to the uterus. Such changes may make a prolapsing (slipping down the vagina) uterus more noticeable. An evaluation by a gynecologist with experience in "pelvic organ prolapse" may help.
Possible uterine des. Older women often have some degree of uterine decensis, especially if they have had several vaginal deliveries. In rare instances, they will eventually require surgery.