Talk to Dermatologist on Irritating Skin Rash

Hi I wanted to seek help for my aunt, For some time now she has this reddish skin rash type stuff, that increases exponentially when she's in high temperature (hot weather or Kitchen), when the dryness in weather or to her is high. She can only wear pure cotton, any other mix type of fabric causes the problem to increase. Skin turns patchy redish with high itching. Doctors have so far given her anti-allergy or ointments like dermavet, but nothing has helped. She is also a thyroid patient. Would greatly appreciate if someone could help and get it cured