Hi I'm a 19 year old female a couple of days ago I started having this pain in my arm. If I put my arm out with the palm facing upwards its on the left side right near my elbow. It hurts and I ran my finger down it and my other arm to see if it had a lump and there is, I'm sure its nothing to worry about but its best to be safe.

You should see a doctor just to be safe and sure. But osgoodshlatters disease makes a bump. But I'm not a doctor so I wouldn't know. But that's just a guess. Good luck!