I feel your pain! I had a trip at work a few years ago and wrecked my ankle, it looked similar to yours, it was stupidly swollen and turned almost black all over my foot and right up the ankle. A&e also told me it was a sprain and ligament damage and to try and walk on it.
They were insanely busy and the nurse literally just had a quick look at the x-ray after I asked her if she'd had the chance to look.
I was off work for a fortnight and it took months to get better. Infact its still not the same, I have less movement in it now.
I have also broken the same ankle in the past and honestly, this sprain was more painful, it was the same type of pain only more severe, I couldn't believe it wasn't broken.
Moral of the story is I never went back for a second opinion but I wish I had. I'd do the same if you're worried.