It seems to be one of the serious side effects of Nuva Ring, my friend. Here is waht I found for you:
Any of the following may indicate a serious vaginal ring-related complication. To remember, use the acronym A-C-H-E-S.
-Abdominal pain, severe (especially if located beneath the lower right rib cage)
-Chest pain or shortness of breath, severe
-Headaches, severe
-Eye problems, blurred vision, flashing lights or total or partial blindness
-Severe leg pain (calf or thigh) !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Hopefully, it will help