✔ 最佳答案
If you don't mind me asking, how old are you? I had the same problem and when I went to see a doctor he told me I was having growing pains. It's called an Osgood-Schlatter Disease, and it might continue until you stop growing. (The female body doesn't stop growing until around the age of 18.) For some reason I only got them behind my knees too.
Check the link in my sources. It should tell you more about it.