Why is my sister having period pain, heavy flow, white vaginal discharge, and leg stiffness?

Hello doctor,

My sister is 17 years old, with a height of 5.3 feet, and weighs 90 pounds. She has white curd-like, colorless, and odorless vaginal discharge with no itching for the past four years. She has not consulted any doctor or taken medication for the problem until now. While waking, her leg and waist become stiff, and she experiences pain. Hence, she remains in bed for one to two hours after she wakes up. She gets some relief if the stiff areas are massaged. She also has pain in her leg muscles, waist, and neck regularly. The pain increases when she cycles or does hard work. Because of all the pain, she is in a depressed and angry mood all the time. Her periods are painful with heavy flow. When consulted with a gynecologist, she was advised Novelon to get relief. Now, she does not experience pain but still has heavy blood flow. She feels weak all day. Is her condition curable? What are the tests she must undergo? The doctor we consulted locally prescribed her TSH (thyroid stimulating hormone), RBS (random blood sugar), USG (ultrasound) lower abdomen, prolactin level estimation, and rheumatoid factor tests. Please help.