My 4 year old is pooping blood he is also pucking buut no blood what is going on?

Needs to be seen. Blood in the stool can be due to several reasons, but associated with vomiting is worrisome. I would suggest that he be seen by his doctor as soon as possible.
Take him to a doctor. This could be many different things, from infectious diarrhea to allergic reactions to food, to more severe problems such as ulcerative colitis or crohn's disease. Take him to his pediatrician (if he's not been keeping fluids down and is getting dehydrated, take him to the er).