When PMS symptoms are severe, the condition is called premenstrual dysphoric disorder (PMDD) . But PMDD is rare. Your doctor will ask questions about your symptoms and do a physical exam.It's important to make sure that your symptoms aren't caused by something else, like thyroid disease.hen PMS symptoms are severe, the condition is called premenstrual dysphoric disorder (PMDD) . But PMDD is rare. Your doctor will ask questions about your symptoms and do a physical exam.