I have these exact symptoms. I have been stressed recently over a rash I developed on my penis which was caused by rubbing soap on the head and when I washed the soap off, it had a red itchy patch and blister. Along with that, it also had white spots on the under side of my foreskin.
I am negative on all STIs, STDs and HIV, which of course, is a relief. I have no symptoms of any of the aforementioned, either. So I believe stress triggered this condition of mine.