Can't click using trackpad on Macbook Pro (2010)
OK, I did some more troubleshooting and took the thing apart. No signs of battery swelling though I did unseat/reseat the thing. When I put it back together I literally banged on the trackpad until it started being responsive again. This would not normally be my plan but a tech suggested it and, oddly, it seemed to work. 

Long term plan is probably replacing the battery or just replacing the entire unit altogether.