can't install or update apps

Hello,
I have iphone 4s with a jailbroken iOS 6.1
This morning I had 3 new apps updates notifications in the app store. One of those apps was Whatsapp. The moment I clicked "update" I received 2 messages, and all the updates were frozen on "waiting..." I rebooted my iphone, but it didn't help. Also clicking the app didn't help. I tried signing out of the appstore in "Settings", and later signing back in at the "App Store" app, but nothing changed. Eventually I deleted the apps, but when I tried to download these apps (and other ones), it remained stuck at waiting...
Then I went to itunes, downloaded whatsapp, but again it was stuck. Then I rebooted again, and FINALLY whatsapp started installing...
So at least I have now whatsapp back, but any other app that I try to download from the app store encounter the same problem (stuck at waiting). It would be a real hassle to update or download apps only through itunes from now on. Is there a way to fix this?

Thanks!