I'm going to be making an appointment to see the doctor this week concerning this, but OOI I thought I would post here and see if anyone had prior experience, then compare my crowdsource diagnosis with the medical one!
The injury in this case was caused when handling livestock but I am sure a similar injury would be possible through sports and so on.
Outwardly there are no signs of injury - no swelling, redness etc.
When I hold my arm out straight in front (or indeed at any angle for that matter) and rotate my hand anti-clockwise, there is a sharp pain on the inside of the elbow/bottom of upper arm muscle and down my forearm. If I attempt to force the hand beyond the point of pain, the pain gets much sharper and more significant.
At rest there is a bit of a dull ache to the general elbow area.
Not sure about the internet, but the doctor will first want to know which arm, and whether you're right or left handed.
Right, and right.