Hyper pigmentation in neonate

This 17 days old baby girl developed such mottled hyper pigmentation on face and rest of the body since last 2 days. There is no h/o prior rash. There is h/o fever on day 5 after birth for which baby was admitted by pediatrician and she received 5 days course of ampicillin, Inj.Gentamycin and Inj.Ceftrioxone. It was normal delivery but at 36th week of gestation. Except for pigmentation she was otherwise normal.

Acute generalised exanthematous pustulosis (AGEP)

This patient presented to me with sudden onset of widespread non follicular pustules over his body. He did not give personal or family history of psoriasis. My diagnosis was Acute generalised exanthematous pustulosis (AGEP). AGEP is a condition characterised by sudden onset of non-follicular aseptic pustules all over the body. Among drug-induced skin eruptions, AGEP is remarkable by its short time to onset after the administration of the suspected drug (less than 24 hours) and the great predominance (80%) of antibiotics as causative agents. Though it is generally easy to elicit a drug history in AGEP, I did not succeed. After 2 days patient called me and told that he remembered taking an Ayurvedic concoction called arishtam on the previous day of erruption. A literature search showed that, after drug reactions, the most common causes of AGEP are acute infections with enteroviruses, and hypersensitivity to mercury. Without taking sides, let me refer you to this article here:
http://faculty.washington.edu/chudler/ayur.html