The problem might be your battery. My battery expanded.
I have the original battery that came with the computer. A couple weeks ago my trackpad wouldn't allow me to click. Also, the bottom of my computer was starting to get very hot. Hotter than it should.
So I looked at the bottom of my computer and woah and behold the battery had cause it to kinda rise up. I took it out and instantly I could start clicking again. So not being able to afford a new battery at the moment, I decided to just leave the battery out and tape my charger to my macbook. My laptop then became a desktop.
Ghetto.
I kept the battery because im way too lazy to go recycle it at my local Best Buy.
I opened my drawer today and noticed it had expanded more! The photo above is how I found it in my drawer. I did not go trying to open the battery.
That black you see inside feels squishy. So I now believe its time I get the battery out of my house before I get radiation poisoning and grow a third arm.
I guess what im trying to get at is; if you have an older Macbook Pro and your tracking pad stops working, check out your battery. It might just be blowing up.