Red ichy skin on penis

[AmericanInJapan]

I have been dealing with itchy genitalia for the better part of the summer.  I'm living in Japan now and the temperature and humidity is much higher than what I'm used to back in the north eastern USA.  That being said, I've been living in Japan for 4 years, and until this summer I never had this problem.

About two months ago I went swimming and stayed wet for the whole day.  The following morning I had a horrible case of heat rash on my inner thighs.  I found a cream that remedied this, but then about two weeks later my scrotum started to itch.  I don't think this was related to the heat rash, but I don't know.  

This case of an itchy scrotum persisted so I went to my Japanese dermatologist.  I showed him the redness and explained the symptoms, and he seemed to think it was hives.  I had eczema as a kid, but I never had eczema or hives on my genitals.  Anyway, he gave me about two weeks worth of antihistamines and told me this would go away when the weather became cooler.  That was about 4-plus weeks ago.  

Over the past week or so the red itchy area seems to have moved to the under side of the shaft of my penis, particularly where the shaft rests on my scrotum.  I am getting a bit worried about this, because it's becoming worse.  The doctor also gave me an ointment that I've been applying for over 3 weeks, but I have stopped as of today because it doesn't seem to have any effect.  I just applied a Japanese hydrocortizone.  The itching has stopped temporarily, but I don't know what to do.  I tried searching the web, and I can't seem to find anyone with a similar ailment.  

I would like some professional advice.
Thank you.

[AmericanInJapan]

Thank you for your advice.  I have been applying Lamisil AT for a little less than a week now, and it seems to be clearing up.  The redness has almost completely subsided, and the itching has drastically been reduced.

Thank you so much for your counsel.

[Bhupinder Kaur, MD]

Hello,
I cannot confirm anything without examination but it can be jock itch. Jock itch shows up in post-adolescent men and hormonal changes during puberty, lifestyle and heredity each play a role. Predisposing fungal disease like tines cruris may also aggravate it.
Wash your groin daily and then dry thoroughly by pat drying, not rubbing. A hairdryer is useful if you have hairy groins. The damp groin is an ideal site for fungi to multiply. Also wear cotton underwear and change them twice a day and do not share other people’s towels. Application of local antifungal cream(terbinafine, clotrimazole, econazole, ketoconazole, miconazole) and oral antifungal drugs are the mainstay of treatment.

If the symptoms persist then a dermatologist’s evaluation will be the best.
I hope it helps. Take care and please do keep me posted in case you have any additional doubts. Kind regards.