snakes normally emmit a mixture of liquid with solids (as I am sure you are aware) similar to bird feces. If the solids are powdery the snake has digestion issues. I dont want to just say constipation, but something of the sorts possibly. Something is making the solids more dry than normal. As for the liquids having blood tinge to it, it may be a parasite. Coccidia for example can cause bloody stools in cats or dogs. Either way, take in a fresh sample to your vet. They can run it for parasites. Some may not be able to do it "in house" and may have to send it to a lab. Make sure the sample is fresh. You can put it in a ziplock in the fridge. Do not freeze.
Hope this helps. This is by no means the definite, exact or only answer. Call an exotic/reptile vet. They may be able to help you a bit over the phone or at least guide you on the right course. I would at least do a fecal test, especially since the snake stopped eating.
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****Misty****
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