Aww Sweetheart, I'm sorry that you are going through all of this. First of all, you do whatever you need to do to be at peace, if you need to go to the emergency room, and you can afford it, just go. Just to make sure that is' isn't some kind of infection or something.
I have pains that sound similar to that, especially in my elbow, or near my ribs. I have back/nerve issues so I think it's that. It isn't normal, I'm sure, but it isn't as harmful as your mind could make it out to be.
Personally I don't think it's any kind of cancer, I think it may be some bruising, or some sensations that your body's getting used to. After some trauma like that, it takes a while for your body to feel somewhat normal. (It's never going to be normal, especially as you age accident or not). So don't be scared. Pray, and accept the peace that God give to you. You'll be fine.