Battery drain 5%-0% in less than 30-40 sec (Galaxy a5 2016)

Hello guys, i recently came across a small drain from 5%-0% battery almost 5 times.
I am not a power user, i mostly listen to music,use camera and browse the net, (NO GAMES).I own the phone for about a month which came out of the box with android Marshmallow and almost 50% battery.
I'd be glad if ppl could give me explanations about the drain and tips to fix that.
Thanks in advance!

Thanks for replying Jacques,i use my phone only for camera,music and browsing, no other apps, screen brightness is mostly on very low and screen drains the most of my battery. (although when i firstly got the phone i kept playing real racing 3 heavily for 3-4 days). Although battery life is incredible, my problem is that after reaching 5% battery life it goes 0% in just some seconds, without even using it,and i'm afraid it might get worse.

— modified on Apr 17, 2017, 6:40:06 PM