Need seo expert help...

Hi Friends,

I am working as SEO, i need your help that i have been working for a website for 4-5 months my website is ranking well in google. Before 3-4 days i have added a new product page. I worked for that and it started performing well but yesterday when i checked rank for that product. I found that i have lost rank for that product. Can you please help me to know that what can be the reason ?