Problems with my Mac and iCloud documents

I am having a lot of problems with documents in the iCloud in the last couple of days. It seemed to have started when i was having problems with an app not syncing correctly between my mac and my ipad & iphone. Now it seems that when I try to open that same app, or pages,numbers and keynote....it acts like it is going to open up, but then doesn't and i have to 'force quit' it. Any suggestions on how I can fix this?