I could tell you what it sounds like, but I don't want you going to your mother and saying some random lady on the internet said it was XXXX.
What I will say is this: If she continues to ignore you, tell another trusted adult. If your father isn't in your life, then a grandparent, aunt, uncle...if you still aren't being listened to, then maybe a friend's parent.
I've had something almost exactly the same happen and it's nothing too serious. (Mine was a pinched nerve.) I went to the doctor, got a prescription and then went through physical therapy for several months. I still sometimes have issues, but I know what to do when it acts up.
Like I said tell someone and make sure you get seen.