Polycystic ovarian syndrome (PCOS) is a very complex condition that involves many different parts of the endocrine system and reproductive system in women who have it. The syndrome is associated with the development of ovarian cysts which is how it got its name, though they don't usually cause any problems. Probably the most common symptom of PCOS is irregular periods. These irregular periods arise from cycles in which ovulation (the release of an egg from the ovary) does not happen. They can also make it difficult to get pregnant. PCOS is also associated with weight gain, type 2 diabetes, and abnormal hair growth (sometimes facial hair). Not all of these signs need to be present to make the PCOS diagnosis.
If you are worried about your roommate's health, then I would suggest that you talk to her about it. Perhaps even show her this answer. She needs to schedule an appointment with her primary care physician
or OBGYN. After a thorough interview and physical exam, the doctor
will likely be able to tell whether or not she has PCOS. Perhaps there is another reason she is having irregular periods. Depending on the severity of some of the complications of PCOS, she may warrant a referral to an endocrinologist
for further work up and treatment. I hope that answer helped.