Very beautiful cb rt you have, always nice to see a cb over an import. I had a Hermann with simular symptoms, almost no apetite, almost no activity, and rare very wet/dierriah poop. My vet diagnosed internal parasites without a fecal test because it simply wasn't possible to collect a sample. Sure enough week 3 of 4 of the treatment my 6 inch Herman pooped out a nearly 4 inch long worm during his daily bath. A few weeks later he was in tip top shape. Possible your little one picked something up in the garden, or from home grown food.
Dont think its bacterial based because you havent mentioned any labored breathing or oculare/nasul discharge. Speaking of bacteria, it's hard to tell from the pictures but in the picture of the hide it seems the back wall is stained. If your enclosure isn't sealed and is just bare wood, the wet substrate will cause the wood to eventually mold/rot and harbor harmful bacteria.
Only other idea i can think of is the same as the others, impaction or blockage from substrate. Hope your little one feels better soon! Also, just a side thought, you might have a undeveloped male. Cloaca looks more like a slit to me (male) then a star (female).