Excuse me Eccles - Psybbo, it flared up about 6 weeks before my wedding in 1997. I had to have steroids orally and cream (put on 2 stone) and UV treatment thrice weekly - YAY, sunbeds on the NHS. The spots eventually disappeared after about a year and I've had no recurrence. Although I am ever so slightly sensitive, the slightest blemish and I go a bit loopy. It was awful. It ruined my wedding day. I had a backless sleeveless dress, which had to be altered to cover up the fact I was covered in hideous spots and smacked on some weight.
It took a long time to be diagnosed cos my GP was insistent it was chicken pox. It took me throwing a massive hissy fit for him to refer me to a dermatolagist. It was thought, at the time, that my PLC was a reaction to my then boyfriend having shingles. Other than that it was diagnosed as "idiopathic" - ie we have no fekkin idea.
It was an awful time. I have immense sympathy with your daughter. it is so rare that people just dont "get it". Please reassure her, it WILL go away just as quickly as it came.