Hello,
It can be due to ringworm or dermatitis skin. You need to get it examined from a dermatologist to confirm the diagnosis. Treatment is diagnosis specific. What you need to do is consult a dermatologist and get a KOH examination of the skin scrapings of the penis and a biopsy of small skin sample done if the symptoms persist. KOH examination of the area will clarify whether it is due to fungal infection or not.
You should also maintain hygiene and try to keep the area clean and dry, wear loose-fitting cotton clothing. Also use an antibacterial soap or mild soap like dove. Avoid deodorant / cosmetics. You can also use calamine lotion or cream with zinc oxide paste applied directly to wet skin after bathing.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
A more zoomed in picture
http://i.imgur.com/PULvQRf.jpg