Happened yesterday but I don't know when, I didn't notice at the time (do not an obvious sting etc).
The red patch is about 3inches by 2 and spreading slowly (was faster - last night it was like a standard small bite). In the centre there's a yellowish area. There's a lump under the skin which is also growing, it's almost as big as the red patch. The whole thing is raised and hot.
The red spot to the side is separate to this.