Antacids did this to me. I was convinced it was electrolytes, would take supps etc but I believe it came down to calcium absorption. Taking a break from the antacids immediately stopped the cramping.
The reason I asked is that creatine will allow you to lift a bit more (a little more weight, a few more reps). This will cause more muscle fatigue which in turn can lead to more cramping. Water and electrolytes can help, but when the muscles are fatigued they are still more likely to cramp.