Hi... Welcome to healthcaremagic forum...
Giddiness while bending down is probably positional vertigo. This is not part of the symptoms of head injury
Did you lose consciousness after the fall?
Do you suffer from severe headache?
In the absence of headache, vomiting and or loss of consciousness; it is unlikely to be a case of head injury. The swelling is probably a scalp hematoma
which should resolve in few days with rest.
If the dizziness
persists, consult a doctor and you may need evaluation which can include brain scan and x-ray of the cervical spine
Hope this helps.