My Facebook page seems to be frozen. But everything else works just fine. Don't know what to do.

I have an Iphone 4S. several years old. All of a sudden as I was using FB, the screen used to direct post froze up. I have tried turning phone off and on several times. Also tried volume buttons. the posting page will not move. I have OS 8.1.2 with 31 applications.

Have no idea what caused it. i have tried pressing the screen down with no movement still.

Every other application works fine: phone, messages, photos, notes, everything else.

Just the FB white screen with Share or Send or Copy or Save Link screen is frozen.

Help