Hi and welcome to the forum! I am glad that I can help you.
You want to know the cause of the symtoms that you experience.
After being punched in the abdomen, people may experience pain due to bruising of the abdominal muscles. Frequently during closed abdominal injuries, the spleen may rupture and individuals may experience symptoms that suggest hypovolemic shock such as dizziness and fainting.
According to the data that you described, it is likely that the abdominal pain is caused by the punching. Take analgesics to treat the pain. Since you pointed out that you fell from height and blacked out several times, you may need to have a CT scan of your head to exclude possible intra-cranial bleedings and hematoma.
Please keep in mind that I provide medical information only. I am not able to diagnose medical conditions online. Please contact your doctor for further advice and information about diagnosis and treatment options.