DANGEROUSLY HOT IPHONE BURNS MY HAND

My phone gets so hot that it literally burns my fingertips or hand. No background apps are refreshing. My phone is not in hot weather, but is in a cool environment and is not being charged at the time this happens, which is every single time I use my phone. All background apps are closed. It is just dangerously hot and blistering my fingers. I just replaced the battery a month ago at the Apple store, yet my phone won't keep a charge more than an hour and it's always burning dangerously hot. Why?