Rogue´s poo was barely recognizable in its usual shape and texture, although it was not watery. It also smelled awful!
Looking back, I think the cause of this was this plastic substance she had been chewing on. Luckily I got rid of it and have not had the problem since.
So, try and think if there´s anything that he may be eating that could be causing it, I wish I had.
I was also wondering, could this be impaction? Maybe someone else with more experience could help out here, but it did pop into mind.
Check out the info. on Guinea Lynx as there may be something familiar there. Also, don´t hesitate to take him in to the vet if you are unsure or your intuition tells you otherwise. It is much better to be safe than sorry.
I hope this helps a bit.
I've also been told that bananas are good too, but then there was some debate about administering this. If he has not been fed bananas in the past and it is not a part of his routine, then he's better off without it.
Let us know how it goes!