iPhone 5 Battery Drain issues

My phone, is experiencing battery draining issues, i ruled out the jailbreak possibility and fresh start possibilities. It only holds charge for barely 3 hrs at most. I'm wondering if this would require to open up the phone and remove the battery and replace it with a new one. My battery guage jumps significantly from time to time and sometimes my phone will shut off at around 30% or so and just die. Also, is the Battery ifixit sells an OEM part manufactured by apple and not by a Third Party? Thank you.