The best thing you can do in those moments are to go to a meeting, find something right away to do to take you away from those thoughts, or call sober friends. I had it when those times blindside you.
I have felt great in the morning and by the last afternoon I have craved like crazy out of no where. The other thing I hate is waking up in the morning and either had using dreams or feeling like you woke up with a hangover. That's the worst cause it really ticks me off cause if I am going to feel crappy I at least want to have done something fun to deserve it!
So...keep tudging forward. Cravings and triggers suck!