ER doctors suck. They are always in a rush so it is fairly common for them to miss or missdiagnose something.

A few months ago when I wrecked my bike I knew I had broke my collarbone because I could feel the 2 bones moving against each other. The ER doc told me that I had an AC seperation, and no broken bone. Despite me telling him and showing him the break. When I went to the specialist I found out the bone was broke at a sharp angle and comepletely seperated by that time.

Last year I broke my hand after going down at the track. Same thing basically, they tried to tell me it wasn't broke only bruised. Turned out it was broke so bad (close to a joint in the hand) that the doc had to put 4 pins in to help it mend.

But in your case, it deffinately would hurt to get a second opinion to be sure it isn't broke.