If your usage hasn't changed, then it sounds like it could be defective. I believe it has a one year warranty, so I would contact Roku support (this forum is not Roku support). In the meantime you could use an app on a phone or tablet to control your Stick.
One other possibility is if you're using the headphone jack in the remote. If so, leaving the headphones connected when not in use will drain the batteries in a day or so.
Dan Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.