Our nine week old puppy has been having a slimy jelly like blood substance when he poops what could be wrong with him? I found him with a mouse that possibly had contact with rat sac the mouse wasn't torn open though, could he have boon poisoned ?

If there is a possibility that your pup could have gotten into rat poison, then it is best to get him to the vet, most rat poisons work by preventing the blood to clot, in effect the mouse or rat bleeds internally until dead.
Of course there are other things to consider also, appetite, activity, gum color.
Whether he has been dewormed or vaccinated and when.
Have you changed his diet?
Gelatinous, slimy poop may be an indicator of a stomach upset that he may need medication for.
Could be something else entirely.
I think the vet is your best option here.