It could be gall bladder, I have had that for years and I noticed the few times I had surgery and had to only drink fluids for the day prior the pain would go away, just something to keep an eye on or get checked out.
I'm also 15 and I have the same problem. My mom's a physician, so I asked her, and she said it was fine.
I have anxiety, too, which is why I never Google symptoms because bad things always come up :/