Why does it hurt when i masterbate myself?

Yu get the most from this site when you provide detailed background information that describes the issue followed by your question. What are you doing that hurts? Does it involve outer clitoral stimulation, inserted objects, etc? If you provide enough information a site doc may be able to formulate an answer. As written, your post does not.

Do not insert objects into your vagina. If you search the internet, you will find a way to amuse yourself through clitoral stimulation and that may avoid the "hurt". Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines