Two aspects, besides mental illness of course, are at play here.
1. No real consequences and
2. Power: its one thing they control that gets a reaction from staff and other inmates.
First I suggest that the next time this behavior occurs get a really, really strong deodorant. One that stinks in its own way. Each time you make it clear the deodorant is a reaction to the smell of the crap. Next: keep the reaction /comments to a minimum. So there is no sense on her part of having an impact on anyone. Over time it should decline /stop. If not then sneak in some dog **** and drop it off in her cell... she'll get the idea. Best of luck.
I have been on a decline. I have gained tremendous weight. I became obsessed with it. It isn't power. My female body is mine. I was a cheerleader. Always exposed in the limelight and had to wear tight mini skirts. Well, I could only do that for so long. I got tired, I felt like my body was everyone elses. I didn't feel safe (for a long time) now that I have healed I can say it wasn't power, it's inner brokenness.