Roxey and Angus (Huney had it when we first got her too) both had this. Everytime they would have to poop, it would be runny like diarriah. The vet gave them panacur dewormer. You couldn't see the worms, but when he did a fecal he found them. Maybe this is what Nebo has? I hope so.
I personally don't think it could be parvo, because Angus had that when he was a very small pup (8 wks) and ohhh....he was soooo sick. He kept thowing up yellow mucus, he got dehydrated, couldn't eat, drink or hardly move. But you definately should get him to the vet.
To take Huney for this it costed me $51. This included the medication (3 days worth), fecal exam and office cost.
Just wanted to let you know!