I have what Some nurses have described as contact dermatitis. In addition, I have been checked for herpes, syphylus, and chlamydia in which the penis had blisters but the results were negative. But my penis sort of aches with redness, my arms feel like acid, and my skin has raised whelps at times with a sort of yellowish lined blister. My penis head throbs and has red and sometimes blackish spots- wow, I don t understand.