Based on the fact that you have stated It appears that he may have sustained injury
to his Frenum( as rightly thought by you). during a forceful dry intercourse.The dizziness
and head ache may be due to Vaso Vagal shock due to severe pain
that he had.There is nothing to worry . Have a look at his Frenum if it is injured just do daily dressing and cleaning and apply Topical antibiotic
ointment.Avoid sex till it heals completely.