This is a second degree burn, as it has blistered. This means more of the skin was affected than the epidermis, or upper most layer of skin.
Redness with blisters is considered a 2nd Degree Burn.
It depends on the sevarety. If blisters form, then it is 2nd degree.
3rd degree
If she has never had chicken pox before, they could be chicken pox. They might also be insect bites or acne.
Excema
Any spider bite can do that.
Sosmontonic
The sap of some types of Hogweed can burn the skin and cause blisters.
It looks like a combination of a red patch and a blister.
A chemical burn.
If you are fighting a virus or if you have a cold you might get a fever blister.
Precipitation