Samsung Galaxy S6 — Issue with S6 Edge battery rapid drain

I'm currently having a battery issue with my S6 Edge and was wondering if anyone has heard of it or something similar and could weigh in.

Essentially within the last week my phone has just been endlessly eating my battery faster than usual. It's to the point where I'll have my phone on airplane mode and the battery will still drain pretty rapidly. I'll be lucky to get 2 hours screen on time, much less if I'm using Wi-Fi or data. As I'm typing this sentence it went from 100 down to 97, it's insane. I've tried holding down power, home and volume down and it reset it but the issue persists.

Another thing that's happening is while charging it will have the green light indicating the battery is fully charged, but it won't be. For clarity, I've never dropped the phone from a height that would cause major visible damage, so it's really out of left field that this is happening.

I've googled a good bit and there's no clear explanation or fix for what's going on, let alone a solution. I'm debating getting a new battery installed but figured it might be best to ask others before putting money down, battery replacement costs €70 so if anyone has any advice or could recommend a course of action I would greatly appreciate it.