There are different causes of quick seminal discharge. Due to inexperienced sex, overactive bladder, improper techniques of sex, too much anxiety etc. Without taking proper details regarding your health status, any other factors like diseases, smoking drinking, previous status of masturbation etc I can't presscribe proper medicine for early ejaculation. For details regarding that problem you should consult me online on this site with an appointment. Skin darkness on the inner thigh areas is common and irritation is due to high moisture content mainly in this summer. You can use dermicool powder or candid power (if intense itching and redness with patches) and don't wear wet clothes or underwear soaked with sweat. Don't wear underwear at home or at night. It's better.