unwanted lock screen appeared. help?

several weeks ago a new lock screen appeared - out of nowhere - and now won't go away. I've tried to manually go into setting and change it - no luck. When I restart my s5, my original screen (which is still selected in settings) comes up, but is then taken over by this lock screen that won't go away. I'm running Themer - thought it was associated with that, but I've since cleared cache/data/deleted it, with no luck. This thing doesn't keep time, give any notifications, or swipe responsively. A real PIA. It also affects the notification bar - won't give me my notifications. Same with the lock screen - occasionally I will swipe my screen and see the original notification bar, but mostly this new one. Any thoughts? I'm really not keen on wiping the whole thing are starting from scratch.