What Could Cause Skin Flare-ups (around Underwear Straps) And Severe Itching?

I have these skin flare-ups, especially on my bra and panty straps. I have this constant itching in my scalp and body. No dandruff. I create small scabs by scratching. I've tried clobetasol propionate cream, different shampoos, different body washes. It gets worst when in stress. I do not take any medications other than vitamins. I am 60 in good health, except for this. I've been experiencing this for a year on and off. Please advice!