Based on the information that you provided, there could be one of many reasons that you are experiencing these complaints of dark circles around your eyes. It would be recommended that you discuss these concerns with your primary care doctor
who would be best able to evaluate your medical history, and presenting symptoms and decide upon the appropriate medical work up. They may recommend imaging studies or referral to a specialist. The other concerning feature that you described is the issues of joint aching and diffuse body pain. There are many autoimmune disorders that may be the cause of this, or a constellation of other disorders that may be the underlying cause of such severe muscle aches. This can include lupus, rheumatoid arthritis
, RSD, as well as a variety of other disorders. These are unlikely related to PCOS. It would be beneficial to discuss these symptoms with your primary care doctor as well as the two complaints may be unrelated but they may be able to work up both complaints and alleviate a lot of the complaints that you are describing. The other possibility is that your sleep patterns may be disturbed by the underlying diffuse body pains you are describing, in which case, the treatment of the diffuse pain may improve your sleeping patterns and decrease the dark circles under your eyes.