iPhone6 running hot and draining battery

Mine started doing that yesterday. There is some app that is draining the battery, probably doing something it shouldn't do. You need to find the app. As a start go to Settings/General/Usage and tap on Battery Usage. This will list the apps that have used power in the past day, ranking them by the percentage of the power used.

For me it was the Calendar app. I have turned off Exchange calendar syncing, and I'm tracking the results now. Facebook is a very common offender.