D.B.
Except for the bite on her forehead, this sounds like black fly bites. We get them here in central Mass earlier in the spring - the small flies are called May Flies. They are bigger in NH and Maine though, and their season is longer I think. I get bites from May Flies that are exactly like what you describe - hard, red - the center part is often raised up sort of like a mesa in the West! My bites can get to be 4-5 inches across, and they itch like crazy. They can also be very hot to the touch. You can try ice and some spray-on anti-itch stuff (like hydrocortisone). Rubbing a cream on it just irritates it and worsens the itch.
Spider bites can vary in size. They often occur in a series and follow a line - they get in tight spots like under the elastic in a waistband, or under a bra, and they bite in that line. I'm not saying that's the only pattern, and different spiders might do different things. I don't know that nausea and hard abdomen are all that common, and there are thousands of species of spiders so I'm sure there is a lot of variation. I'm just speaking from my own experience as an oft-bitten person!
You didn't see bugs, but they're there!!
