I had a similar problem happen to me. The wireless mouse was just getting worse and worse, regardless of whether new batteries were in there or not.
I'm sure I was driving my playing partners nuts with what looked like 'practice swings' but it was just that the mouse was stopping by itself short of my intended swing strength. Then it got worse when it just started making a second click by itself, so I started to get whiff shots. It was a classic confidence-destroyer...
... so, eventually, I got a new mouse, which is wired, and is 100x better.
If you're going to fork out for something new, I strongly recommend going for the wired option, as it removes/reduces one of the many connection variables.
Good luck!