Hello there and welcome!
I think a few things can suddenly affect battery drain.
A common culprit is an OTA update--did the device have a recent update?
A recently dowloaded app, or misbehaving app--have you added any apps lately?
A good app to narrow down rogue apps is Gsam battery monitor available in the PlayStore.
As far as the slow charge bit, it could be that the rogue app is sucking juice while charging. It also may be a wonky charger or (being as the device is just over a year old since its release) a battery going south. (I'm not really sure its the battery though as they should last longer than that for sure)