Go to Settings, and tap on Notification Center. Find Facebook, and turn off notifications.
For this, you may use the vacuum nozzle, and slowly and carefully clean the buttons. With all the debris and dirt which is maybe all around the button, issues are possible, and it may be the reason why the music randomly increases and decrease on your device.
If the volume buttons are “stuck”, you should press them often, fast and hard for a couple of seconds. It may help.
Another solution which worked out for many was the restart. Press and hold the sleep/wake button, and once slider appears, drag it, and turn off your iPhone.
First, backup your files to iCloud, and once you are done, you may continue. Go to Settings, tap on General, tap on Reset, and choose Erase all Content and Settings. When the task is finally over, you will have to set up your device as new.