What Causes Cravings For Ice Post Gastric Bypass Surgery?

I am a 38 year old female. I had gastric bypass surgery May 2014 and now I am craving ice and to chew on dish sponges (weird and had the same cravings when I was pregnant). I am not pregnant now (tubal). My hemoglobin was 10.3 about 3 months ago. Could the cravings be a result of my low iron? Or another vitamin deficiency? Also I have been getting my periods every 3 weeks for the past 3 months when normally they were every 4 weeks. Associated with the other problem?