Feces Question...

[Zoe]

Okay, here's the deal. I got a fecal done on my boa when he first defecated, and the sample came back negative. Anyway, he just defecated again tonight and it's somewhat greenish. The urate itself was white, the feces were dark brown and normal-looking (but there wasn't very much of it) and there was also this greenish, watery, gooper stuff.
Now, the first fecal was done on a small sample, so is it possible there was a mistake, and that the snake does have parasites?
Or could there be another reason for this? I recently found out that he was lost for two months before I got him (and he wasn't fed between his being found and his being acquired by me), so is it possible he's just expelling the last of the gunk that was in him from roaming around with no food for two months? Could that also explain the small amount of feces and large (normal) amount or urate?

Any insight would be good! I will get a second fecal done to make sure, of course, but any info would be much appreciated.

Thanks!
Zoe