Hi, last night and this morning I've noticed an extremely worrying problem with my iPhone 4S. I unplugged my phone from the charger this morning at around 10am and when I checked back at around 3 (without one bit of usage) the battery had gone down to 54%. Now I left it again from 3 untill just now at around 5.10pm and the battery has fallen now to 20%!!! I haven't used my phone all day, I've ended all running apps but the battery is dying so quickly and the phone feels warm. What could the problem be? Should I take it into the Apple store or is there something I can do myself to fix it? PS. I noticed that this happened last night, but has never happened before then.