I was getting the shopping from the car boot, and the boot fell closed on my left forearm. Immediate pain.. I can move my fingers, and support myself on that arm, though ot is a little sore after i stop putting pressure on it. To touch it, is about 3-4 /10 ( i have a high pain thresshold) i have a raised lump 10cm in diameter, sore to touch. Could i have a hairline fracture? Or just tissue damage