No abnormalities are detected on examination.

The haemoglobin percentage is 9 g/dl. The coagulation profile and the ultrasound scan are normal.

1. Oral contraceptive pills for 3 cycles. 
2. Mefenamic acid 500 mg 8 hourly during menstruation. 
3. Norethisterone 5 mg three times daily for 7 days during menstruation. 
4. Norethisterone 5 mg twice daily for 3 cycles of 21 days. 
5. Tranexamic acid 500 mg 8 hourly during menstruation. 

Mefenamic acid 500 mg 8 hourly during menstruation. 

Since she has heavy menstrual bleeding and dysmenorrhoea, the best option is treatment with mefenamic acid. Treatment is commenced on the first day of menstruation and continued for the duration of bleeding. Tranexamic acid will reduce the menstrual blood flow but has no analgesic effect. Cyclical treatment with OCP is also effective but is not considered as the first line therapy, for heavy regular menstrual bleeding and dysmenorrhoea, as long treatment cycles are required.

https://www.nice.org.uk/guidance/ng88