I seriously doubt tabacco was to blame unless they ate a whole lot of it ,it's been used to worm dogs and catsGoodness, I certainly hope no one put poison out... In a nefarious way. We do not use rat poison in my home or outside due to the animals (and dogs; they get into everything). We actually don't have any poison or traps (other than bug traps that are all inside and hanging fly traps outside). My partner smokes loose leaf tobacco; is there any way that if some of that dropped onto the ground and they pecked it up that it could cause death? I wouldn't think that much would get out, though... So probably not.
And I am on a very fixed budget right now so I may not be able to get it completed if it is too expensive. I have been reading online and the most common response is coccidiosis (especially at their age). But I would think that it would happen one at a time, not all four within two hours?