welcome to healthcaremagic,
from the description of your accident it seems more of an ankle sprain
with damage to the vein they ruptured due to the impact of the board.
i would suggest get an xray done to rule out a fracture
and if symptoms persist and the red blotches dont disappear then you need to get a mri
done to see the state of your tendons and ligaments and blood supply to your foot.
would suggest you visit a doctor for clinical checkup and appropriate investigation and appropriate treatment.
hope to have answered your query.
wish you a quick recovery.