Battery won't charge, hold a charge, and meter doesn't work.
Over the past few weeks, I've noticed the battery on my iPhone 6 has just experienced a ton of problems. Sometimes, the meter doesn't accurately reflect how much power I have left - it'll say I have 40%, then suddenly shut off, and when I plug it in it shows that the battery was dead. Other times it tells me that the power is less than 10% but when I plug it in it immediately jumps to over 50%. When I charge it, it takes a long, long time to charge, and the battery drains constantly. I have everything shut off, no programs running (I even signed out of iCloud after seeing on the forum where that helped other users) and my battery just dropped from 58% to 38% in about 20 minutes.
I want to say this got worse after I upgraded to the most recent iOS, but it's been getting bad for a while now. Any ideas? I've shut the "push" function off entirely, and I now have to manually fetch my mail. Nothing seems to be working.
iPhone 6, iOS 8.3