rear end shunt

8 days ago a 18 wheeler forgot I was infront of him in a trafic jam and started off. he hit me on the rise and then stopped. We jerked forward then back and I hit my head firmly again the head rest, the pain in my neck was almost imedeate. My question is: could this have caused a black eye? as I have now got one and I have not nocked it in the mean time. The reason it as only just been noticed is that it is across my upper lid and my wife saw it (saturday sleep in) when she woke up and looked at me?