Talk to Dermatologist on Nail/skin Issue

Please refer to the picture I am attaching. My mother-in-law (aged 61 years) has developed this condition in her nails during the last 1 month. She also recovered from dengue last month and this condition was first noticed during that fever. There is no pain associated with it and she previously has suffered from massive hair loss (around 2 years ago) which was very much improved using perfectil on a daily basis. Any possible causes or leads towards diagnosis would be highly appreciated.