Why do I have sore on penis frenulum?

Allergic dermatitis can lead to redness, itching, and swelling in the affected area It is necessary to find out which allergen is causing the reaction and avoid it. I suggest you to see a dermatologist for proper diagnosis and treatment.
 

Acne is multi-factorial problem, hormonal disease in most of the patients, diet, exercise, hygiene, grooming practices play important role.so visiting dermatologist and taking treatment is one option and maintain treatment for long time because if you are getting any improvement with the treatment then continue it otherwise dermatologist will change it. there are few things that has to be taken care. One thing not to apply hair oil, avoid having dandruff or use anti-dandruff shampoos weekly on the scalp, using face washes that have salicylic acid or glycolic acid. Avoid using thick greasy moisturizers or cream on the face. Use only creams that are gel based or water based. Drink plenty of water, avoid fat or cheesy diet, exercise 10-15 mins of the day. Topical steroids have to be avoided. Topical antibiotics like Clindamycin are useful. Oral Antibiotics or retinoids are advised. 

This could be a case of dermatitis which is a skin condition caused by such things as allergies, irritants, or infections. To make this disease go away, try not to get in contact with any irritant, wear loose clothes as well as the right detergent, and apply mild soap. The use of a sensitive skin moisturizer can soothe your skin, as well, and be the ending part.

Fungal infections can make your skin red, itch, and sometimes hurt. These infections usually like to grow in warm and moist places, so butt skin can be the common spot. To help mop it up, keep the area clean and dry, wear loose clothes, and apply antifungal creams or powders that the pharmacist recommends. To get it if it still comes back, you may need a stronger prescription from the doctor to get rid of it.

It looks as though you burgeon an umbilical granuloma which is a small piece of tissue that protrudes from your belly button. The yellow discharge may be an indication of the infection. In some instances, it could come on without any pain or swelling. To do this, you have to keep the area clean and dry. It is also possible that you will need antibiotics when the infection gets worse.