Hi Lybrate user
You can go for a USG scanning of Pelvis and Hormonal test for Progesterone
Its may be due to hormonal changes.
You can use Tablet Rajpravaratani vati two tablets two times a day to stimulate uterus for menstrual cycle.
Use Syp Rejoton 20 ml two times a day empty stomach to regulate menstrual cycle.
Avoid oily spicy fried foods.
Tc Thank Regards.