I should also mention that your problem can also be just a natural sensitivity in witch case id still recommend the peroxide and also a black skin care product call "high time bump stopper"(you can buy it at almost any drug store).If your black or white it will still work for you, just black skin is generally more sensitive after shaving,Its a cream you apply after shaving and at night.
change your razor regularly ,rinse your razor in diluted hydrogen peroxide after every stroke and your face afterwards ,this should stop you from continuously reinfecting your skin and alow it to heal over time .you still have to treat it, most likely bacterial lots of vitamins, water and garlic pills. your doctor can also give your creams and antibiotics some over the counter, if its fungal no antibiotic should be used and your doc will give you a different kind of cream.