Derobin is strong cream containing salicylic acid and dithranol which needs to be used only if prescribed by qualified dermatologist and as per proper instructions. First of all stop this cream right away and the side effect that you have developed needs to be checked properly. You might have developed irritation or allergy to this which can be treated with anti allergic creams and tablets.
Next Steps
Send pictures showing affected areas along with query for proper treatment.
Health Tips
All the best. Take care. Regards Dr.Jeetendra Khatuja (Mumbai)