Without seeing the lesions, it would be impossible to say what they are.
Possibilites would be a bacterial skin infection, dermatitis or a fungal infection. Excessive masturbation can be a possibility resulting in dermatitis. The use of lubricants or steroid creams can help with that.
If the cause is determined to be fungal or bacterial, appropriate topical creams would be a reasonable therapy.
Of course, there are other causes, such as various forms of STDs and genital ulcers (i.e. syphillis, chancroid, or herpes). An examinination by a dermatologist or your primary care physician can help in the evaluation.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.