About 2 weeks ago, within hours of some vigorous sexual contact (consisting of manual stimulation by both parties and brief oral sex by her, but no penetration other than by hand), I noticed what appeared to be some redness and slight swelling around the rim of my glans penis (I am circumcised). It was localized to the rim of the glans on the top half of the penis.
Because it appeared so quickly, and was not accompanied by any blisters, sores, pain, itching, discharge, etc., I assumed it was just physical irritation and basically ignored it. When it faded but didn't completely disappear 11 days later, I went to see my primary care doctor, who did a very quick examination and stated that it was just "local irritation" and not an STD, etc.
However, that was about a week ago, and the redness (perhaps faded somewhat) is still there, still localized to the top rim of the glans. The only other thing I may have noticed is that a strip of skin about 1-2 cm wide below the rim seems to be a littler paler than usual and more sensitive to the touch. But I'm not sure about that, and I can't really see anything unusual other than the redness.
I've searched high and low on the Internet for pictures or descriptions of anything resembling this, and the best I could find is a photo of "Balanitis caused by Citrobacter." (If you go to this website: http://atlases.muni.cz/atl_en/main+dermven+foreskinpath.html and click on photo #2825, you'll see the slight redness and swelling around the rim that appears similar to what I have.)
So I have two questions. First: Is my self-diagnosis correct and, if so, how should I be treating it? I applied topical antibacterial cream intermittently for a few days, but didn't see an immediate change and wasn't sure whether to continue. Second: If I'm wrong, is there something else this could be and/or anything I should be getting tested for?
Thanks so much.