Hello, Anon! Thank you for posting.
Sores, blisters, or bumps on the scalp or face may be caused by:
Infection of the hair shafts ( folliculitis ) or the skin (such as impetigo ).
An allergic skin reaction ( contact dermatitis ).
Viral infections, such as chickenpox and shingles.
An underlying medical condition.
A skin condition, such as acne.
I'm not sure why your accident would cause this to occur. See your doctor for a proper diagnosis. Keep us updated.