Hello,
It can be due to fungal infection or erythrasma skin. Erythrasma is a chronic superficial infection of the intertriginous areas of the skin.It is true that groins are effected but the typical appearance is well-demarcated, brown-red macular patches. The skin has a wrinkled appearance with fine scales.
It has to be differentiated from contact dermatitis,psoriasis,sweat dermatitis and fungal infections which may mimic it.Wood lamp examination and gram staining are the tests for its diagnosis.
So nothing can be confirmed without examination. 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 dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
hey man whats up... hope your penis is doing better.. look i am pretty sure that its not an std or something that you should worry about i know that its on a sensitive spot.... i had mearly the same sympoms with you but only on the headof the penis and a bit further low...i went to my dermatologist and he told me that it was fungi and gave me an otc cream if i recall corect it was VERDAL look dont self medicate..... but with no strees and no anxiety andwith zen mind..... go to your dermatologist and show him your penis...... hope that helps ohhhh and dont masturnbate constantly makes it worst..... cheers