Trackpad going crazy
It's probably moisture.  

I experiencing something similar after being caught in the rain with my MacBook Pro.  Working outside because the weather was nice, I got caught in a slight drizzle of rain.  I immediately shut the lid and ran inside.  

It didn't get wet enough to cause damage, but somehow wet enough to mess with the clicking function of the trackpad; it would sometimes "lock" in the clicked position, not register clicks, or click erratically.

What I did was put my MacBook Pro in a Zip-Loc bag with several desiccant (silica gel) packets and leave it overnight.  



In the mid-morning, I took it out of the Zip-Loc and the trackpad was working again.  

I save these packets in a jar; they come in the packaging of products I buy.  I will throw some in my camera bag where I keep my lenses and I will put a few in my briefcase where I keep my laptop.  

If you save them, they're free, but they are also extremely inexpensive on Amazon or eBay if you don't have any available and are in dire need.