Hi there Adria!
At this age it seems to be one thing after another doesn't it? You finally get them off the night feeds and all of a suddeen they wake for a different reason!
What is Jency up to developmentally at the momnet? A lot of these random night wakings are caused by them hitting some kind of 'milestone' whether it be physical such as rolling, sitting or crawling, or more mental such as clapping, waving etc. Everything throws their sleep for a loop!!
All i would advise it to be consistent with your methods and don't 'accidental parent' your way through and create any other new problems that then need solving!! No matter what it is caused by, he will come out of it in a few days, when he realises that there is nothing to wake up for!!!