Default [Q] Fast battery discharge

My Nexus 4 is just over a year old. It has been performing really well throughout this period. A month back, the soft buttons on the screen stopped working and I got the screen replaced. The phone was working very well even after this. I am running only the stock Android. I haven't rooted the phone yet.

Over the last few days, the battery discharge has been fast and unpredictable. I have attached the Battery screenshot. I shall explain the sequence of events to describe the screenshot.

The battery goes from 40-50 to 0 in one go! (the first downward steep drop). Phone had already switched off. I connected it to a charging point and restarted the phone.

While the phone was being charged (the slow upward red slope), I did some research on this. Since, Google Play Services was consuming most of the battery, the following solution seemed to be good to follow.

(Disable Hangouts, sign out of Google+, turn ON Location Reporting, reboot, then reenable Hangouts and sign back into G+),

I tried this. Once I rebooted, the battery power was 56% !! (The steep upward climb)

I used it for some time. And kept it on charge to charge it completely. But after some time, the battery charge dropped to 19% (the second drop in the screenshot). I rebooted the phone again. And this resulted in the next battery charge spike upto 45%!!

I tried searching for Hangouts app or Google+ app on the phone. But they no longer exist in the app drawer.

Is this a battery issue? Or some software issue? Should I try a factory reset?

Edit1: Added a larger image of the battery stats.
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An avid Nexus 4 fan !!
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Nexus 4 - 4.3 hopefully!!
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