LG Nexus 5 - Overheating, Battery drain.

Starting a month and half ago my LG Nexus 5 would get hot near the camera (Where the CPU is) and drain the battery unusually fast, even without an active app opened, now I can not keep it on outside because of the drain and even if it stays connected to a charger, it slowly builds a charge because of the drain.

I recently changed the battery and the problem continues to persist.

This started happening around when I went over all the settings in the phone and apps, I fear I might of turned on something that is causing it in the background but I can not figure out the exact problem.

Please help.