Hi i am Dr Ahmed Aly thanks for using healthcaremagic site , I had gone through your question and understand your concerns .. In my opinion , i dont wont you to be worried and for may patients i suggest icing it for the first 48 hours , NSAIDS painkiller like advil when needed , massaging it with topical gels , elevation your left leg on a pillow and avoid bending will be effective for such cases . For the numbness actually its quiet rare but happens when trauma or the swelling affect the nerve supplying this area which will subside when swelling decreases . Otherwise i recommend X rays to exclude minor fissures or fracture on your shin bone . Please click THANK YOU and consider a 5 star rating with some positive feedback if the information was helpful. Hope the above information helps you, Any further clarifications feel free to ask.