Injecting - Good God, got no nod!!

[m.swinehart81]

So swim has been having alot of issues with his veins lately and there is one that has been untouched. This would be his femoral... He has tried to hit it before but never had any luck. He tried today for the first time in a long time and thought he had it. So swim pushed in the plunger and about the time that the plunger was half way down he got a wierd feeling in his chest and his head started to pound like you wouldnt believe. His leg on the side he shot up in turned red as well. At first swim thought that maybe he hit the artery but every time swim has hit an artery else where on his body he has always got the sort of elctric burning feeling but he didnt feel that this time...
Is there anything else that could cause this or is it most likely that swim hit his artery?