iPhone 4 lost sync?

Hey guys,
I was just trying to wirelessly put some songs on to my iPhone from my MacBook but my MacBook won't recognise the phone? What I mean is that it won't wirelessly sync with it, it comes up on the devices list for a few seconds and then dissappears. I tried plugging the iPhone in & syncing via USB but iTunes says that it is synced with another computer and it needs to be restored from a backup?
Any ideas on what I can do? My most recent back up on my MacBook is about a month or 2 old and I can't lose all that data :/ it has been recently backed up to iCloud but if I restore it from that backup won't it do the same thing that it is at the moment?
Thanks in advance.

 

Anyone? 260 views and no one has any idea?