I've read the rule sheet available on the Oneworld site and can't understand what has changed in the past 48 hours, can someone help?
Yes. The rules have just changed. The copy of the rules on the Oneworld web site has not yet been updated (and in fact the web site is now showing an old version of the rules - from 1 July 2013)
The changes are being discussed in the
Changes to the xONEx Rule Sheet thread - see from post #66 onwards.
Sadly, your itinerary is no longer valid