Hi yes yes, purging does make you have mood swings,firstly because your body is not getting the fuel it needs ,so all your hormones are all over the place,and your body is not realiseing the happy hormone endorphis because think about it how do you feel afterwards,pleased that the deed is done but then exusted..
Please get help,it sounds as if it is starting to control you now, iknow exatly how you feel!!
Take care
lovexxxx