RASHES ON SKIN. Lasting rashes.

Have a rash on shoulders and back for last two months. Started after three plus days of no bathing and same clothes usage due to lack of water and electricity in a extremely hot and humid area. Rash bump subdued but still pigments remain. Consulted a dermat had a one month course. All blood tests like cbc, sugar, cholesterol, creatinine, thyroid ok. Lft reveal bilirubin 1.4 but sgpt, sgot ok. Had hiv and hepatitis test before marriage in 2011. All negative. No risky behaviour of any type no blood transfusion or any drug abuse. Completely polygamous. Wife also tested during pregnancy. Completely ok and healthy. All blood tests done at good reputable laboratories injections for vitamin d deficiency taken from registered medical practitioner from first use seal pack disposable syringes. Worried about recurring/long lasting rashes.