It happens sometimes. Our girl does this occasionally... looks normal at first and then a bunch of less digested matter that sort of "spatters about" her
bath tub. I make sure to double check basking temps, and also make sure that she gets nice long baths for a few days, to up
hydration. We had a bout of this a couple of weeks ago (a few days in a row), and I realized that since she started pooping ONLY in the
bath, her baths were sometimes ending up short (once she poops, she's outta there and sometimes that's fairly early in the
bath--within a few minutes), and perhaps she was getting as
hydrated as she should have been. So now, I "poop her" in the small Rubbermaid tub, and right after transfer her to the big tub for a nice long soak/swim. Also, because we'd gone from very hot weather (where I had to raise the basking bulb--MVB), to a cooling trend, I did find that her basking temps were a tad low--not overly so, but possibly enough to affect thorough digestion so I adjusted the bulb down a bit and since, all poop has been ok.
Hope this helps!
Em