There have been plenty of times when I've had no weekly loss, or even gains. It's important to look at things in the long term, I think, and take stock of what you've managed to acheive so far. Mixing up your exercise routine is a good thing, but don't beat yourself up for not having had a loss.
Here at the end of my weight loss, I have had many weeks that I didn't lose anything. I try to stay positive and eat according to plan and get my exercise. I know that eventually the lbs. will come off. It is frustrating but it is good maintenance practice and each week that I don't gain, I am happy. Good luck to you and know that the lbs. will drop, just stick with it. It happens to us all.
I know how you feel. I've been losing and gaining the same 5 pounds for a month now. >_<.. I don't know if I should cut out calories or just work out harder.