It definitely sounds like she's trying to make a bowel movement or trying to pee. I can always tell when Shilo is trying to poop because his head will go straight up in the air and his mouth will open just a little bit. There is also the worry that she may be constipated but you can usually tell because there hasn't been poop in a while and there is a bulge at the base of their tail. If that's the case, just place her in some water about the temperature of your hand, maybe a tad warmer and it'll pull that right out. I give my snakes baths weekly, and that'll work like a charm believe me.
Shilo scares me an awful lot, he's a pastel and he'll do weird things with his head (like lay it up against his hide at a 90 degree angle... sleeping perfectly) and one time I even caught him limp on his branch like he was dead, but he was just sleeping like a rock. O_O