Sudden bending of spine (forward or backward) can cause injuries to the ligaments and muscles of spine, which are responsible for holding the bones of spine together. Apart from the external bruises that you have, there is possibility that spine and/brain may have suffered minor injuries (because you have dizziness
and headache). I would suggest you to consult doctor
immediately to detect any minor injuries that you may have suffered. For external injuries pain killer medications and antiseptic ointments
may be sufficient for a few days.