Can you vomit from not pooping?

Long term constipation can develop into fecal impaction, which involves hard, dry stool becoming stuck in the rectum and blocking other stool from passing. A person with fecal impaction may feel the need to have a bowel movement but be unable to push anything out. Fecal impaction can cause pain and vomiting.

Can you throw up poop from being so constipated?

In severe cases of bowel obstruction or constipation (such as those related to clozapine treatment) fecal vomiting has been identified as a cause of death. Fecal vomiting occurs when the bowel is obstructed for some reason, and intestinal contents cannot move normally.