Slow iPhone 5s

I have a iPhone 5s I had gotten it around five months ago so its fairly new. It started running slowly a few days ago also the message to log into iCloud has became extreamly more frequent (I can't log into iCloud because it has the wrong email and won't reset). Most apps load quicly but sometimes it won't allow me to accsess my texts and will close itself out of it. When I try to close tabs by pressing the home button twice it freezes for around a minute or so . I've tried restting it and shutting it down but it doesn't work please help!