It was not very wise on your part to consume two tablets of nimesulide, which is not at all indicated for headache. This drug is either banned or not permitted for sale in almost all advanced countries such as United States, Britain, Canada, Australia etc. for causing severe side effects. Now that you have developed severe skin reaction, you need to take anti-allergic medicines and steroids. Your doctor has already prescribed the same. It will take a few days for the symptoms to disappear. In future do not take this drug; otherwise you may land up in more trouble.