Yea we need more info!
That being said I can tell you that Facebook CAN be a data and battery drain. It constantly checks the internet for updates, and uses your cellular radio, and your data. Now data impact will probably be ok, BUT it can kill your battery, especially if you have an older iPhone with a battery that is not at peak performance, and of course certain Android phones which inherently have bad battery life. I had to take Facebook off of both my mother and my father's phones. I made them homescreen web links to the mobile Facebook site instead, that they can check as they want or need to.