It might be strongyloides if pinworm med don't work.
Read ICU strongyloide protocol.
Recurrent rashes are known as larva currens or creeping infection. It occurs from strongyloides autoinfection and appears as an eruption beginning in the perianal region that rapidly spreads and causes intense itching. Episodes usually last several hours before subsiding again for weeks or months. Because of autoinfection recurrent larva currens may continue for many years, often decades.