Try drinking a lot of water today - 0 carbs (i.e. not cream, no sweetener, no "allowed" foods that have even trace carbs) and limit salt intake, then weigh yourself again first thing tomorrow morning. This 3 pound gain may be related to water retention (especially if you ate something particularly salt packed yesterday or even some hidden carbs from sausage, spenda brand sweetener, cream, etc).

Just a thought....

ETA: Are you on Atkins '72 induction (DADR or DANDR?)