Icloud - does my friend sync my iphone and ipad to his icloud without telling?

Last summer my friend downloaded an app (game) on my iphone through his icloud account. He logged on through his itunes, downloaded the game, and logged off. I did not see exact what he did. He said he used 3G. After this, my phone has had periods where it is not working. Just an hour or so, then workes as ordinary.

My friend then sent me his apple-is to log on to, to get the game at my ipad as well. I logged on his apple-id, and got the game. Then I suddenly now discovered I was logged on to his Icloud account (saw it at settings). The ipad was connected to wi-fi for a whole day like this. My question is: was my ipad sync'ed with his icloud when I was logged on, and if so, did my passwords, pictures, the webpages I looked at, my facebook-conversations copied and saved at his icloud? How can I figure this out? 😝