Hi Doctor- My Sister's Age Is Around 20 Years, She

Hi doctor- My sister's age is around 20 years, she is having sound health, but, she is having trouble with her periods- she haven't had period since 3 months. She visited a gynecologist and she was told that she has water bubbles in her uterus. Even after having medicines for couple of weeks, she hasn't yet got periods. What would you suggest under these circumstances, like diet, what kind of food she must have. Anything else you would suggest. Thanks- Ranjani