Apple Watch saying no space is left

I started tracking my sleep with the app SleepWatch, and for a month my watch was totally normal. Now for the last month, every once in a while I wake up to a notification on my watch saying that my storage is full and my watch only tracked my sleep for a few hours. Then I have to hard reset my watch, because it acts like it can't track anything anymore. My move rings don't go up or my stand hours. I only have 3 apps downloaded on my watch that didn't come with it, and none of my usage matches what my storage capacity should be. It says that I have used all 4.8 GB with 0 bytes available, but the biggest app on my watch looks like it is my Mail app, and that is only using 34.4 MB. I'm confused and frustrated because this has basically made my watch unusable.