Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Most of the times, genital rashes are caused due to sexually transmitted disease. Does he have any discharge from his penis? Also is there pain and burning during urination? Do you also have any infection or the above mentioned symptoms on your genitals? Doxy would work but I suggest you can get him reviewed in a community or a government hospital if its not affordable to visit a private doctor. I would also suggest maintain good hygiene, drink lots of water and increase your nutrition quotient. Hope that helps!