If they attach to the ovaries they are called endometriomas cysts (image). Here they form into blood filled cysts which can induce painful periods (dysmenorrhea), cramps and even infertility. Endometriosis tend to cause the worst pain out of all the different types of ovary cysts.
While some may believe that the incredibly high rate of use of Nexium and other PPIs means that they are essentially safe, these medications actually raise the risk of a number of side effects which are very serious or even potentially fatal, including the risk of acute kidney injury, kidney disease, or even end-stage kidney failure.
It is recommended that you take Nexium an hour before a meal (which means the same as on an empty stomach). This is because food can significantly reduce the amount of drug that reaches the blood stream. Hope this helps. https://www.drugs.com/nexium.html.