Did the poopie have any jello-y consistency to it? along w/the red blood @ the end? That's a sign of colitis, inflammation of the lower gastrointestinal tract or colon. It can be caused by a high fat diet...raw food has a higher fat content.
Princess has a very bad episode couple of months ago & she had to have similar treatment. Penicillin & B Vitamin shots, subcutaneous fluids & amoxicillin. Just 2 administrations of the anti-biotic stopped her runs & bloody poopie. She was staying w/my aunt & she was giving her table scraps & pieces of seasoned steak, which has a lot of fat.
I know they also had a bad ant problem, so lots of pesticides were used inside & outside their home...which also contributed to stressing out Princess' already compromised little system.
The vet also said to give her a bland diet of boiled white chicken breast & white rice along w/fiber veggie, like carrots or green beans for a few days to settle her tummy...but you're already home cooking, so you got that covered. I would love for her to be on raw, but she just can't handle high fat foods. She needs to be on a strict high fiber, low fat & grain free diet.
Hope he'll feel better soon!