Guppy just ate her babies and now will not stop eating or pooping long stings of poop and the poop is sometimes clear but mostly dark in color do you think this could be a parasite or overeating?

Guppy eating her babies could indicate stress or a behavioral response, which might also lead to overeating. The long strings of poop, especially if they vary in color, could suggest digestive issues or potential parasites. It's best to monitor her closely and consider consulting an aquarium specialist or veterinarian to determine the underlying cause and appropriate treatment.