Doesn't look much like my DS's post-viral urticaria.
His looks like a heat or nettle rash - just lots of little bumps, red to start with but colour fades after awhile.
I get urticaria as well - mine starts like DS's but can develop to something more like the picture. All the spots seem to sort of blend together into big raised patches. They look almost like fluid filled blisters, but a lot bigger.