Sounds to me like some sand impaction too. Get rid of that stuff ASAP! Did you ever figure out what the "stringy stuff" was that was hanging? Just fecal matter? I think sand is a bad idea for leo's in general. Most people say just babies and juvies shouldnt be on sand, but from all the experiences Ive had/heard of, I wouldnt keep ANY leo on sand since its not necessary. Many people disagree and thats fine, cause chances are an adult wont get a sand impaction, but you never know.
Speaking of... my local Petco recently pissed me off more than usual. Last week when I went in there I found that out of ALL the herps and inverts they keep there, the baby leos were the ONLY species that they were keeping on sand! Grrr... I told an employee about how they are all probably going to get impacted and die, but as of yesterday those babies are still on sand. They really dont give a s**t about the health of their animals, but there is no way Im going to "rescue" 15 babies who probably all have impactions by now. I just feel bad for the poor saps who go and buy those babies, and wont know why they arent eating and just withering away..
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Anyways, just take your geckos (all of them, not just the bloody one) off the sand and get rid of it. Thats just about all I have to say about that, sorry for rambling.
Joe