The Reaper is offering the best advice- see a physician. Without seeing the lesions, from what it sounds most docs will diagnose it at "contact dermatitis" and prescribe a topical steroid cream if it is a contact dermatitis, or localized skin allergic reaction.
A bacterial infection like SwatSurgeon is describing could be more serious and steroids would only worsen, hence the importance of seeing someone who has a clue.
As an aside, was she wading in water, wearing water shoes, standing in flood water? History is important. While the management may not be different it's helpful to do some detective work and figure out what caused it to PREVENT it from happening again if possible.
For example I got a terrible hive-type rash on my chest, armpits, and inside of my arms while surfing, so much that it ruined my vacation and I couldn't sleep for days. After seeing a Dermatologist and being diagnosed with, you guess it "Contact Dermatitis", I was disappointed with the vague diagnosis and did my own research. Turns out it was likely "Sea-bathers eruption" from jelly-fish larvae and the "rash-guard" I was wearing while surfing was what allowed the larvae to get trapped against my skin and sting me.
No more rash guards in late summer, I'd rather deal with the chaffing.