Why is my battery suddenly draining so quickly?

[Android Central Question]

I own a HTC 10 and it is now around 2 years old. Since last Sunday morning my battery started draining incredibly quick. Prior to that Sunday I have never had any problems with the battery, which makes me feel that something has been downloaded that is causing the problem. I have trying uninstalling apps (that I added), using battery saving mode and even did a factory reboot; however, my battery continues to drain extremely fast. When I checked the Apps inside Settings, I noticed that the app, WLAN Hotspot, is using a huge amount of battery (currently 252% use since last charge). The problem is that this app is built into the phone so I cannot remove it. I have tried 'disabling' and also clicked 'force stop' but my battery still drains at a lightning rate. Anyone have any suggestions as to what I can attempt to do next?

 

[nowifiandroid]

Silly question, but have you checked your wifi settings that you aren't accidentaly using your phone as a Wifi hotspot?