If it is period pain which tablet is suitable

Treatment of painful menses

it is common condition which is known as dysmenorrhea. It is deu to unexplained causes thus firstly you have to increase your daily intake of water for at least 3 liters pre day in addition to vitamin C juices like lemon and orange. Just you can take analgesic to relieve pain like Ibuprofen 400 mg three times daily. You can also take vitamin B6 tablets like pyrodixine tabs daily.

Investigations to do

There is no tests for like condition but you can ask for uterus

Advice

You can seek your gynecologist for further evaluation