our dog was netured 2 weeks ago, now his scrotum sack is hard and looks like he now has marbles ... is this?

Generally, there is some degree of hematoma, or filling of blood that happens to the scrotum after neutering. That resolves and then it is smaller and sometimes harder. The "marbles" that you are feeling are probably the "ends" of what was left.

I had 2 dogs neutered recently and their sacks were still sort of big for a while but they said that was normal. Eventually it went flat about week 3 but if your intuition is telling you that its not normal, do take you dog back to the vet who did the procedure. I did take mine back when the stitches didn't look like they were healing right and the vet didn't charge me for the visit.

He has probably bled into his scrotum. When dogs are neutered, if all of the tiniest bleeding blood vessels aren't stopped, they can bleed into the scrotum. It's probably nothing to be concerned about. I'm sure it's a little uncomfortable, though. Try warm compresses to reduce the swelling.

it sounds like there is a problem. are you sure he was fixed right??he should be flat with an empty bag!! call your vet to see what is going on he might have some kind of infection in there. he has had plenty of time to heal call the vet!!good luck.