1- Try to force close the app. Get the list of apps open up on your device and shut it down from there (If you don't know how to do this, look up how to force close an app on your device). Then reopen it.
2- Try to reset your device by turning it off and then turing it on again and log in to the game.
3 - If 1 and 2 didn't work, try to uninstall the game from your device (you must be sure you have an Origin account linked to the game before uninstalling it, otherwise you'd lose all your progress.) and when you've uninstalled it, re-install it and log in to it after it completes the installation.
4- If 1, 2 and 3 didn't work, the only thing you can do is Contact EA for Help.