I have a patch of dry, flaky, red skin on the head (glans) of my .?

Initially I thought it might be an STD sore, however all the tests (gonn, syph etc.) came back negative. It is about 1cm across and is not painful (just very very slightly itchy if touched). My doctor suggested it might be fungal so I obtained some chlamydia cream but after 4-5 days there is no improvement. As a precaution I have not had any since noticing it, however I did masturbate with some (Wet Stuff) lube about 2 days ago and this caused some discomfort, a slight burning sensation. I am circised. I am prone to eczema at this time of the year but I have never had anything like this on my before (though I do experience an occasional outbreak of , I take valacyclovir on prescription to control this. I am sure that the current condition is not -related). Can anyone ist before I return to the doctor?