With all Garmin problems, the customer support will suggest resetting. First, a hard reset of your watch (power off, leave for awhile, power back on). Then if that doesn't work, they'll suggest a factory reset. I was having some battery issues and they suggested that. (I didn't want to do a factory reset so I haven't tried that. My battery problem isn't as bad as yours.)
You might also want to find out what software version your watch is on. Maybe you got a new update that is screwed up? It happens. I usually check on the Garmin forums to see what people are saying about the latest update for my watch if I'm having a problem.
https://forums.garmin.com/ you may have to do some digging around to find the forum for your watch.