Can I still drink alcohol after bumping my head? CT scan came back normal, only have a slight headache.

Possibly. The correct answer depends of several questions, was there a loss of consciousness? was a concussion diagnosed? We are realizing more and more that" head bumps" especially bad enough to warrent a CT scan, are not without problems. The brain is a fragile organ, trauma and alcohol are both stressors to good function. Best to consult your treating physician.