Take on the battery drain

I am. It sure if this is a common issue but I have spoken with a few
people who have had the same issue I have been facing. Ever since I
downloaded the new iOS, I've had ridiculously irregular battery life.
It's not just that the battery now sucks -which it does- but rather
that it we jump from say 35% to 21% in two minutes. It doesn't seem
to be a huge issue when the battery is at 85%, but when you get down
to below 40% the battery indicator has no relationship to the actual
time left.

The other odd thing is that sometimes, it will just shut down because
the battery has drained from 10% to 0% in like 30 seconds with no
warning. But when you plug it in, the phone is immediately back up to
23% or something. So the phone actually has some juice but it
believes it is actually empty.

Apple, figure this out because I need an answer before I shoot myself