It seems that you may be having irritant or allergic contact dermatitis
on shin of leg. There may be some cause. Soap,clothes,dust,pollens,insects...etc may cause. But, your lesion is improved and you have no complaints except bruise,which may be due to excessive scratching , do not worry. Take antihistaminics like levocetirizine
and apply mild steroid
cream to prevent further itching... I hope you may be alright within few days. Still, you consult dermatologist
.. I hope you got my answer.
Dr. Ilyas Patel M.D.