Your friend may be having an acute generalised eruption of urticaria that can take long to control if not on optimal medication. 80% of people with urticaria do NOT have allergies but respond to long-acting non-sedating antihistamines like allegra, levocet etc
If the rashes leave a scar, bruise then a separate condition called urticarial vasculitis
may be the problem for which a skin biopsy
with special stains will be required. You should ask your friend to see a Dermatologist
Lupus has several menifestations like photosensitive rash
on face, arms and legs (exposed to sun), but also with arthraligia, arthritis
, serositis, blood changes, immunological abnormalities (like positive ANA test) and several other systems may be affected.
So it is very early to tell unless at least 4 of 11 criteria are fulfilled to be labelled as lupus.