Going by your history and ongoing drowsiness
, headache and nausea
, I would suggest that even it was minor injury , you should get a CT Scan
brain done. If the report is normal and your headache gradually subsides you wont have anything much to be worried. Just keep a watch that there is no deterioration of sensorium, severe headache
CT Scan brain ( plain)
See an Emergency Physician with the report for detailed neurological evaluation.