Hi. The blunt trauma over the abdomen can have many consequences. You have already developed a few symptoms suggestive of some internal problems. This can be a contusion to any internal organ, perforation of the bowel and so on. The best way to get a proper diagnosis is to have a clinical / physical examination by a Surgeon to see the abdomen and vitals like temperature, pulse , BP etc. You have to go for the tests of the blood, urine and stool as well as ultrasonography and X-ray of the abdomen in a standing position. CT scan to confirm any positive findings. I would advise such a patient to get admitted to the hospital for observation and management.