From your description, it doesn't sound like a yeast infection
, as there would be other signs at the tip. The symptoms you're experiencing are closer to a severe case of jock itch. Mild cases are treatable with OTC creams, sprays, and powders, however severe cases, require prescription meds, topical and/or oral. You should really see a doctor at a local clinic for treatment. Otherwise, you need to stick with those OTC treatments for at least 10 days, keeping the inflamed skin clean and dry.