Hello,
Thanks for posting your query.
From your symptoms the red rash which has disappeared can be due to friction rub or sweat dermatitis but brown rash can eb due to pityriasis versicolor. It is a fungal disease caused by a type of yeast that naturally lives on your skin. When the yeast grows out of control, the skin disease, which appears as a rash, is the result.
The spots may disappear during cool weather and get worse during warm and humid weather and appears as light or dark patches on face or chest which do not tan with exposure to sun.
Topical antifungal treatment has been found to be quite helpful and anti-fungal topical products containing ingredients such as zinc, pyrithione, selenium sulfide, miconazole, clotrimazole, and terbinafine are available which you can use. Try treating that with clotrimazole twice a day for 2 weeks under your doctor’s supervision.
Hope that this information helps and hope that you will get better soon.
Wishing you good health.
And i forgot to say this time i notices a fairly big size of a brown patch where my pubes are