I have a 2008 Mazda CX-7 Grand Touring and the alarm goes off completely randomly for no apparent reason.

What is your question?

I did notice the other day after some very heavy rainfall the drivers side doors little black button I usually press to unlock and lock the car was unresponsive and upon digging out my key fob to lock the car, every time I'd lock it, it'd unlock. I tried the other two buttons, one on the passenger door and one on the tailgate and both locked and unlocked the car with no issue. When I lock the car I use the button on the tailgate now and on occasion, sometimes after a few seconds, minutes or sometimes after several hours the alarm will go off and will stop on it's own randomly as well, sometimes it sound the alarm for 2 seconds and stops other times it goes off for about a minute and stops. If I use the key fob to unlock then relock the car sometimes it's fine and doesn't happen again for days and other times it continue to happen randomly for hours. It's gotten to the point where

What makes this problem better or worse?

Nothing

How long has your 2008 Mazda CX-7 had this problem?

happened about a year ago for weeks then stopped for several months and now doing it again very randomly every few days to weeks.