Generalized Pruritic Rash Including Palms. No History Of Contact With

Generalized pruritic rash including palms. No history of contact with anything different, no constitutional symptoms. No meds. Started on ankles and forearms spread to trunk , on palms. Over 2 weeks. Spreading/ getting worse. Excoriated erythematous papular type eruption. Put on topical steroid and oral antihistamine without improvement. Rash on palms doesn't look targeted. Not copper like in syphilis and present only 2 weeks. . I'm stumped. Going to do a biopsy but looking for rule out ideas.....