Suet is made from high amounts of fat which will upset your dogs stomach. The good news is it is not toxic.
I would start him on a bland diet of boiled chicken and rice to help settle his stomach.(1 part skinless chicken Breast to 3 parts white rice) I am concerned with him becoming dehydrated as this is quite serious with dogs. I recommend giving him unflavored pedilayte to replace the electrolytes he is losing with the vomiting and Diarrhea. You can also give him One teaspoon of Pepto Bismol per 10 pounds of body weight for faster relief.Walter
Blood in the stool can be a symptom of many different things and when ever blood is present it is best to have the dog looked at. Though based on the fact that he ate this it is likely the seeds coming though the system and causing the blood. It is good that there is no more blood.
As long as he is no longer having bloody stools this should not be a issue. But it is something you will want to mention to your vet so it can be added to his medical chart.
Sorry for the delay, we had a thunderstorm which killed my power for a little while.